Gleemax interactions
Real Answer

Unhinged cards bend the rules. You and your friends should decide how to handle the situation.

How I Would Settle It

If someone in another game gives you an Ass Whuppin', there's nothing that Gleemax can do about it.

Gleemax must to be referring to spells and abilities in your current game. Otherwise, you would have to choose all targets for all spells and abilities for every game in the entire world. That's impossible to do in a timely manner. Also, by the time Ass Whuppin' crosses over between games, it's too late! It has already been cast, and the targets have already been chosen.

Multiple Gleemaxs follow timestamp rules. The controller of latest played Gleemax gets to choose all targets for spells and abilities.