My two year old’s response whenever he gets a chance to bang on one of my XOs:
“Make a Doggy noise!”
This is a reference to TamTam, a set of musical activities which can play back samples including various animal noises, at different pitches (and also be used for music composition and performance, by the way…)
My four year old’s favourite activity is “typing” in Write, where she has very particular requirements: the font must be sans serif, large and pink, and while she occasionally types “momy” and “dady” or her name, she’s usually content to type screenfuls of the first letter of her name. She also loves typing random “words” into Speak with hilarious results.