I sat in the north endzone, way up by the jumbotron. Most of the fans around us were fine, but towards the end of the game an ISU fan and his wife/girlfriend got in a fight with an Iowa fan. To be completely fair, the ISU fan did not hold anything back when he celebrated anything that went our way in the game. A lot of "F*** Yeah's" directed at anyone nearby (mostly Iowa fans). A large, late middle aged Iowa fan took the bait and started shouting at him, the ISU girl fired back and punched him in the junk. He kicked her, sent her down a row of seats, then everyone nearby stepped in to stop the fight. I'm going to call this one a draw on blame... but it happened and it's kinnick stadium. Fun times.
Most everyone else was perfectly well behaved. Family in front of us was great.
I'll add my take on the stuff thrown after the X td. The line judge on the Iowa sidelines definitely appeared to be the target in my opinion. Security ran over to him and he moved away from the crowd onto the field. I saw a full water bottle nearly hit that ref, but then didn't see anyone else thrown.
I also think the rain might have helped the post game situation. Made people less angry maybe?