As an alumna of WhatsamattaU, I can only add:
because those attending Sky-U-Mah U, never forget.
FYI, the real WhatsamattaU was based upon the various odd ways buildings at the University of Minnesota and the Mississippi River interact, particularly in winter, and then in the spring floods. Rumor had it the "U" was going to take over Harriet Island in St. Paul, for a theater or something.
Rocky and Bullwinkle had other ideas. Frostbite Falls is either International Falls, Minneapolis where Minnehaha Falls is right next to Longfellow's home, or St. Paul, where almost the entire Bluffs are covered with ice falls in winter, as water freezes before it makes the full trip from the upper whatever roads on the bluffs, to Shepherd Road - at river level.
Those in the know claim it's St. Paul, the superior City of the Twins, because the U held many classes at Harriet Island in the years right before the cartoon came to television.
"I am young, whole, perfect, strong, powerful, loving, harmonious, and happy." ~~~ Kato Havas