The most obvious thing I can think of is the moose head. It may seem trivial, but it's theft. Tybalt is going to talk about foul play, and do his drama queen thing around this event. At the very least, he'll draw negative attention to the DIKs.
Taken independently, it's nothing at all, but I think Magnar is aiming for an accumulation of small problems, so that after a while the college authorities will say that enough of this crap (fights, theft, vandalism...) has gone on long enough, and that it's time to disband the DIKs and the Jocks.