I think it's a stage...the 4th  and youngest cat (kitten..Orbit) does that. The oldest never did, but the next 3 did.They also have a bad habit of getting too close to the terlet bowl, and having an impromptu 'swim' (yes, that seat is slippery, ain't it?...;)

I have way too many paperbacks, and they seem to like the idea of 'knock things off high places'...bit, the 'climb to the roof, if we only had the boxes', the bit about bags and boxes in general they love.

oh yes, you own a dog, you feed a cat.

I wish I'd said that.. The Staircase Wit

anahl nathrak uth vas betude doth yel dyenvey..;)