Board Thread:General Discussion/@comment-26037406-20150206023943/@comment-25892460-20150206030226

Here's my ideas if they did crossovers:

Adventure Time: Rigby uses the time machine for something stupid (like getting a free meal or something) and ends up ripping a hole in time, causing some of the AT characters (remember, AT takes place in the future) to come to the current time, and cause chaos

Steven Universe: The guys decide to have a beach party in Beach City, only for a gem monster to attack at the party, meaning mordecai and rigby and everyone else have to team with the crystal gems to stop it.

Gumball (this one would be on a MUCH smaller scale): We find out that CJ's parents live in Elmore, and CJ and Mordecai go there to visit them (yeah, we saw CJ's dad, but not her mom).