A particularly fat, disgusting person in reference to the schoolyard rhyme of the same name:
Fatty Fatty Two by Four
Can't get through the bathroom door
So he did it on the floor
Licked it up and asked for more
Did you see that fatty fatty two by four at KFC ordering a whole family bucket of chicken for himself?
Vagina. Particularly a slimy one. Comes from the Generation 5 Pokemon of the same name.
Man, I popped it right into her sliggoo!