I was reminded this morning of something my cat did when I was about 9, and honestly if I hadn't lived it I don't think I'd believe it!
We had two cats who were sisters. They both had kittens at the same time, so we had 11 cats... one morning when they were 3 or 4 weeks old we came downstairs and there were NO cats. Anywhere.
We went round knocking on neighbours doors asking to check sheds etc, no sign. How can you lose 9 kittens?!
Then one of the mum cats came home, ate some food and disappeared again, which was unlike her. We waited for her to come back and made a sort of harness out of string, attached it to her and then let her out again.
We followed her and the string like something out of Hansel and Gretel and she led us to an empty house at the end of our road. Peeking over the fence we found all the kittens having a brilliant time climbing the trees in the garden 
I have no idea what possessed her to take the kittens here in the middle of the night! And I've always wondered, did she carry them down the road one at a time or did she have them follow her single file like ducklings? Did she have a cat conversation with them all telling them they were going on an adventure?! We got into the garden by asking a neighbour who knew and asked the owner, 'captured' all the cats (who did not want to leave their new playground), but strangely they never escaped again!
I had pets all my childhood and have lots of strange and funny stories but that is definitely the weirdest. Can anyone beat that (or explain what the hell she was thinking?)? 