Just had a thought about this and I felt like dropping it.
Corporate Mundo will have a desk pop up as he sits down at it organise some...Mundo stuff by lining up papers and tapping on his phone for a phonecall. He eventually gets angry at the dial tone and flips the table or breaks it.
Surprise Party Fiddlesticks will have him summon a large cake (about his height) then leap into it, he then pops out doing a party whistle with a "surprise!" pose.
Gentleman Cho'Gath, will sit down at a tea table, pouring himself a cup of tea, then looks around before eating the whole teapot doing a little burp with a "Oop, excuse me..."
What do you think?