a woman who claims she is straight and maybe even has a boyfriend, but sometimes gets drunk and has had sex with other women, and then if confrontend about their ambiguous sexuality claims that it doesn't count because they were drunk.
Joe:your girlfriend got drunk last night at the party and fucked my girlfriend. she's a lezzy!
Bob:she says she's not gay, she just does that sometimes when she's drunk.
Joe:yeah, well she's a six-pack lesbian