Bottom
The person who (could be a boy or a girl) in a sexual relationship is the one getting fucked/dominated/topped/etc. The top is the opposite, (see dominant).
Wallace: Hey, did you know that Harrison is a huggggge bottom? Jackie: Woah, really? Wallace: Yeah! I was surprised when he let me dominate him. I wasn't complaining though, if you know what I mean. ;) Jackie: That's surprising! He sure doesn't look like a bottom! Wallace: Haha, yeah...
By WiltedRose