[1] The defendant challenges the sufficiency of the evidence to support his conviction of a second-degree sexual offense under G.S. 14-27.5. In examining the sufficiency of the evidence, we must assume that the testimony favorable to the State is true and consider whether it establishes beyond a reasonable doubt each element of the crime charged. See State v. Robinson, 310 N.C. 530, 313 S.E. 2d 571 (1984); State v. Revelle, 301 N.C. 153, 270 S.E. 2d 476 (1980). After careful consideration of the State’s evidence in the present case, we conclude that it is sufficient to support the defendant’s conviction under G.S. 14-27.5.
Under G.S. 14-27.5(a), “[a] person is guilty of a sexual offense in the second degree if the person engages in a sexual act with another person: (1) [b]y force and against the will of the other person. ...” A “sexual act” is defined under G.S. 14-27.1(4) as: “cunnilingus, fellatio, analingus, or anal intercourse, but does not include vaginal intercourse. Sexual act also means the penetration, however slight, by any object into the genital or anal opening of another person’s body. . . .”
*468In the present case, the State’s evidence shows that any sexual act between the defendant and the prosecutrix was clearly against the will of the prosecutrix. The defendant admits that “any object” may include parts of the human body, such as fingers. The defendant argues, however, that the prosecutrix’s testimony that “[h]e had put his hand inside my vaginal area,” is not sufficient to show penetration of the genital opening. We disagree.
The one statement quoted by defendant might raise some question with respect to penetration of the genital opening. However, there was additional testimony by the prosecutrix that defendant manipulated her “vagina,” and “that he tried to put his penis into my vagina but he could not . . . get it completely in.” Without further elaboration of the testimony, and in light of the ordinary meanings of common word usage, we find that the jury had before it sufficient evidence from which to find beyond a reasonable doubt each element of second-degree sexual offense under G.S. 14-27.5.
[2] The defendant contends also that the trial court erred by excluding evidence of a prior sexual encounter between the prosecutrix and attorney Jack Carter under the Rape Shield Act. The defendant sought to introduce evidence that on at least one occasion the prosecutrix and Carter had gone drinking at Sh-booms, then returned to the sofa in the reception room of Carter’s law office, and had sex. Defendant argues that this evidence should have been admitted under G.S. 8-58.6(b)(3), which provides an exception to the Rape Shield Act for evidence tending to show “a pattern of sexual behavior so distinctive and so closely resembling the defendant’s version of the alleged encounter with the complainant as to tend to prove that such complainant consented to the act or acts charged or behaved in such a manner as to lead the defendant reasonably to believe that the complainant consented. . . .”
We do not agree that the testimony defendant sought to have admitted reflected a pattern of sexual behavior tending to show that the prosecutrix consented to sexual relations with defendant. Attorney Carter testified in voir dire that he and the prosecutrix had had a romantic relationship and that on one occasion they had returned to the law office and reception room, after *469drinking at Sh-booms, and had had sexual intercourse. This occurred, Carter testified, approximately one year before the prose-cutrix’s encounter with defendant. Defendant produced no other evidence of similar sexual behavior by the prosecutrix; nothing in the record indicates that the prosecutrix was in the habit of drinking with men at Sh-booms and then returning with them to the law office for sex. This single incident involving the prosecu-trix and her boyfriend, a year prior to the alleged crime, does not qualify as a pattern of behavior under G.S. 8-58.6(b)(3), having probative value on the issue of consent which far outweighs any prejudicial effect. See State v. Rhinehart, 68 N.C. App. 615, 316 S.E. 2d 118 (1984); cf. State v. Shoffner, 62 N.C. App. 245, 302 S.E. 2d 830 (1983).
Defendant argues on appeal that the evidence was also admissible under G.S. 8-58.6(b)(2), which provides an exception for evidence “of specific instances of sexual behavior offered for the purpose of showing that the act or acts charged were not committed by the defendant. . . .” Defendant failed to make this argument at trial and therefore cannot now assert it. Even had defendant properly invoked the exception, we note that it does not apply to the facts of this case. Exception (b)(2) was intended to cover evidence that someone other than the defendant produced the injuries or sperm found on or in the prosecutrix. See State v. Fortney, 301 N.C. 31, 269 S.E. 2d 110 (1980). The defendant certainly does not submit the evidence of the prosecutrix’s sexual activity with her boyfriend, of a year before, to put in question the identity of the person who had a forcible sexual encounter with her on 20 February 1984.
The defendant argues further that the evidence of the prose-cutrix’s prior sexual conduct was necessary to impeach her and to establish the defense theory of fabrication. We note first that the defense counsel disclaimed any attempt at trial to introduce the evidence for impeachment purposes, but rather relied on the exception to the Rape Shield Act found at G.S. 8-58.6(b)(3). Counsel stated that while he did not seek to introduce the evidence to impeach the prosecutrix’s testimony, the ultimate effect of its admission under G.S. 8-58.6(b)(3) would be to impeach her. We agree that the evidence of the prosecutrix’s prior sexual conduct with Carter might strengthen defendant’s theory that she sought to have sex with defendant in order to hurt Carter, and so *470might tend to impeach her testimony at trial. Yet, this type of evidence, of prior sex with a boyfriend, has a high potential for producing erroneous prejudicial inferences, e.g., that the prosecu-trix is an immoral or “loose” woman and therefore is more likely to have sex with any man, including defendant. Further, the probative value of the evidence of prior sex with Carter, i.e., what it might add to the defense theory that the prosecutrix fabricated the criminal offense to get back at Carter, is really very small as compared to the prejudicial effect it might have produced at trial. At the in-camera hearing, the trial judge stated that the defendant could introduce evidence that Carter and the prosecutrix had a dating relationship. This was sufficient to present the defense theory to the jury. Evidence of particular sexual encounters between the prosecutrix and Carter, however, would clearly carry a high risk of producing prejudicial inferences, but would do very little towards making the crucial link in the defense theory between the prosecutrix’s relationship with Carter and her encounter with defendant the evening of 20 February 1984. The trial judge’s exclusion of evidence of the prosecutrix’s prior sexual activity was consistent with the letter and the spirit of the Rape Shield Act.
The defendant’s contention as to the trial judge’s failure to exclude portions of the prosecutrix’s out-of-court statement to police was not presented according to our Rules, see Rule 28(b)(5), and we therefore will not consider it.
No error.
Chief Judge Hedrick and Judge COZORT concur.