Haha! In my case it’s a small white dog that does exactly the same. She also pops up and curls up on my lap when I’m sitting at my desk. I have to type one-handed then as I am just cradling her a little to make sure she’s not going to fall off with the other!
I also have to make sure my cat doesn’t fall off. If he does, he will stick his claws in my leg to save himself and then bite me in retaliation for him slipping, because apparently gravity is my fault.
WOAH. Percy (our cat) does exactly this. With my husband’s chair ONLY. Like, Percy will sit in my office chair. In fact he really seems to enjoy napping on it. But he vindictively steals my husbands when he’s working from home. Sometimes I think Percy deliberately lures my husband into standing up so he can take it.