peek-a-boo cat
n: when one's penis reverts into the pubic region via shrinkage, thus creating a peek-a-boo effect, whereas the penis becomes concealed one moment and visible the next; usually occurs in the event of a cold submersion, the presence of fat bitches, FUPA(S), and/or nauseating wenches.
Joe didn't want to go skinny dipping, because he was afraid of exposing his peek-a-boo cat.