Things got a little out of hand between Jonah Hill and Whitney Cummings on 'Late Night' (Weeknights, 12:37AM ET on NBC), though Jimmy Fallon has a theory as to why Hill got so angry with Cummings.
First of all, she was rubbing it in that her boyfriend was his boss, though in actuality he's a co-creator on the new FOX comedy 'Allen Gregory' with Hill. When Hill was getting worked up -- jokingly, of course -- Fallon and Cummings tried to keep it cool.
But then he knocked his cup of water off the couch, splashing some water on Cummings' dress. He immediately apologized, but Fallon started shouting that he needed to stop losing weight. "It is making you angry!" he declared.