Funny thing, the het world has a number of different, contradictory "stereotypes" about us. Its like the "genocide" in rwanda: someone decided to call a bloody civil war something else.
Anyway, here's a short list: 
- Gay people are slutty.
 - Gay people all read Jane Austin.
 - We're all anarcho-marxist iconoclausts
 - Flamers, flamers everywhere
 - Bears are all kinky
 - All gay people like QueerAsFolk
 - GayPride is for gay people only.
 - Anyone who doesn't go to GayPride isn't really gay, is a coward, or is a bad person.
 - We're all vicious, catty or act like the wrong gender.
 - Every gay male, loves only anal intercourse.
 - We ALL carry AIDS
 - Every gay person chooses to be gay.
 - We're all great dressers, are neat, and have a beautifully decorated home. And neat freaks too.
 - Gay people are very different than "normal" people.
 - Anonymous sex for all, all of the time.
 - Gay people cannot have a monogomous relationship. Thanks a lot QAF.
 - All gay people are smart. Yea right.
 - Slutty gay men don't have safe sex, and probably have STDs.
 - All gay people under the age of 25 are uncultured and educated.
 - "It's ok to sleep with someone the same age as your parents". Hello Jerry Springer!
 - All lesbians are mean and scary.
 - All lesbians have one of two hairstyles.
 - All lesbians love Ani diFranco. *(add more)