Sitting on the table next to the bed and throwing efurrything off it - and into Mommy's head while she's sleeping.
Then, when she wakes up, getting back into bed and snuggling her so that she won't get mad.
Then doing it all again once she goes back to sleep.
Know what else is fun? Going down into the dungeon where the litterbox is and yowling really really loud, running really fast up the stairs and through the house and then back down the stairs again. It makes Mommy thing that there is a bug of somefing down there, and she comes looking for it.
But you know what the bestest fun is? sticking your paw in a dish of ice cream while she's eating it. And then when she give it all to you, walking away.