Lesbians are a useful friend to have, for a straight woman. She just has to kiss you, maybe flash her tits, and you'll agree to take the virginity of her brother, or boyfriend, or single friend. It's not like lesbians have any other use than dealing with all the awkward and uncomfortable parts of teaching a man how to fuck a woman.

Sucking his cock and telling him about how to keep it clean and his semen sweet instead of bitter. Showing him how to unhook your bra. Letting him play with your tits, and letting him know that he should be gentler with your straight friend, she probably wouldn't appreciate having her nipples pinched quite that hard. Enduring his spanking, telling him when he's slapping your ass too hard or too soft. Telling him to clip his nails before fingering you. Letting him explore your pussy, showing him how to play with your clit just right. Taking his premature ejaculation raw, letting him get used to the feeling of sex, comforting him about his performance anxiety.

If you are very lucky, your straight friend will let you learn all her pleasure spots so you can train her boyfriend to please her better. Even if she doesn't, you'll still have done your duty to bring her pleasure, making sure that she can get dicked down by an experienced, skillful man. Depending on how close you get with the couple, you might end up in a threesome. So if you have a crush on one of your straight friends, your best bet is to volunteer to train her boyfriend with your body.