The Hart Senate Office Building might as well be a freshman dorm. The rolling prank war between hallmates Sens. Claire McCaskill and Ben Nelson is back on, with McCaskill pulling a stunt this morning to taunt her colleague ahead of tonight’s football game between the University of Nebraska and the University of Missouri.[IMGCAP(1)]The Missouri Democrat snuck into Nelson’s office (well, she did get the OK from his staffers, who promised not to tip off the boss) and hung doctored photos of Nelson wearing Missouri hats, ties and football helmets. One even shows the Nebraska Democrat fishing, but instead of a fish on the end of his line, there is the Missouri mascot, a tiger.Nelson spokesman Jake Thompson tells HOH that his boss got a kick out of the prank, which was only fair turnabout after some of the tricks that Nelson has played on McCaskill (including once when he infiltrated her office and hung pictures of himself over all of her framed pictures).Nelson’s staff retaliated today in a move that has so far gone undetected by McCaskill or her people: They took the Nebraska flag that usually stands outside the Nelson office and wrapped it around to hide the Missouri flag that stands outside McCaskill’s neighboring office.Take that, Tigers!Despite the tit-for-tat practical joke war, in true peacemaking fashion, the two Senators are hoping to watch the game together tonight at Senate-side watering hole Union Pub.Just look out for whoopee cushions on those bar stools.Submit your hot tips, juicy gossip or comments here.Can’t get enough HOH? Get a midday dose of fun and gossip with HOH’s One-Minute Recess, delivered to your inbox daily. Sign up here — because everyone deserves more recess.