My little Ceramen (not celtic, latin. For earwax. Don't ask) used to hang in the cat flap, head in, arse out, waiting for some other cat to come and lick his bum.... He also had a foot fetish and would eat your toes. Shadow is a cat of very little brain, she cannot remember how the catflap works in this house, even though it is identical to the one in the previous house, that she used perfectly happily for 4 years!