Fun as HECK.
I got into MUN my junior year of high school, wish I had gotten started sooner.
Started in legal committee (Not my favorite) but senior year I attended the University of Michigan MUN and was placed as Prime Minister of Japan in a historical recreation of World War 2. We WERE supposed to try and work it out peacefully, but the US delegation wanted to brawl and had our Emperor assassinated within the first 3 hours of talks. We then proceeded to essentially play risk for 4 days. (10 hour days too) I won a gavel at that conference and I couldn't have asked for a better cabinet to have served with. My ministers of the Army, Navy and Interior were invaluable assets and we actually ended up completing a suicide run against the west coast that left San Francisco in ruin and most of the salad bowl on fire. We ended up losing because our sim-Hitler threw in the towel early to try and negotiate a better position for post-war Germany, allowing the Allies to devote all their resources to the Pacific.
It was a brutal war too. As soon as bullets started flying I instituted terror tactics in the field, mass beheadings of POW's and the heads left on stakes. Whole islands covered with mines and not a single Japanese soldier to be found. Mega-doses of combat-meth/adrenaline issued to even the lowliest soldiers (Turns out the stuff is actually super cheap to produce, shocking), mass production of suicide torpedos, all kinds of fun stuff.