pronounced 'gee tap'
Stands for: Great Tits, Awful Personality
This is a girl who you keep around (and hook up with) because of her body, but hanging out with her is not actually an enjoyable experience.
"Don't invite Laura to the party tonight, I can't stand that girl."
"Yeah, me neither, but shes such a GTAP that it's almost worth it."
"I wouldn't sleep with her, but I'd let her give me a blowjob."