You're at a party, and so far the action is slow. The classiest girls there are the ones who don't have cookie crumbs in their mustaches. You're seriously considering going home and thumbing through that used copy of Tit and Bum.
And then...in she walks. A stunning raven haired beauty, in tight revealing red dress, her pert breasts straining against the thin, clinging material, nipples jutting, pouting blow job lips parted ever so invitingly. But you notice, to your chagrin, that she's with another guy.
Here's two approaches for you to try:
This is generally a good party approach anyway - everyone has to go eventually, and you get a great chance to see what's there in the room. Wait till either your dreamgirl or her beau has to go, and pounce then and there. One thing you should keep in mind - just because a girl is with a guy doesn't mean she's REALLY with the guy. He could be her brother, or cousin, or roommate. If he's really unlucky, he's someone with whom she's "just friends," which, being translated from womanese means, "he takes me everywhere and pays for everything, but if he tries to put a finger on me he'll never see me again." Brutal, aren't they?