Just about everyone knows a cat that likes to sleep in the sink.
If you think not, look for telltale signs. Are there strange hairs on your bar of soap....I don't mean the curly ones that you may blame (curse) others for leaving behind, in your home. I mean long silky ones? Is your toothbrush hairier than usual. If you say yes, you may have a secret night-sink sleeper.
I have had 3 sink sleepers. This one is Claw'd (named because that's what you got when you went near him).
This particular cat used to sit on top of the fridge and bat the top of your head when you opened the fridge door, and also hide behind doors, attacking your ankles when you walked past. Sadly this little fuzzy monster is no longer with us.
Slightly less well known...but they are out there for sure, because I have had 2 of them, are the dog tub sleepers. This is Monty, our first tub sleeper (again, no longer with us).
Our current dog will do this as well. She did it a lot as a young dog (as well as dragging out the wet towels and rolling in them). She is getting older now, and it's harder for her to pick her legs up climb in, so we don't see her there as often. I suppose this is a big dog thing, that's what we have always had.
Anyways, cats in sinks, dogs in tubs, just part of the strange goings on in your home when you own pets. Nothing weirder than walking into your bathroom on a warm summer day , and having your sink and tub full of furry animals.
Gotta love 'em, they have their own personalities.