Yes, Mamma Mia is mindless, silly, shallow, meaningless nonsense; the merest skeleton of a story upon which to hang the skin of the Best of Abba. And, yes, it’s a cheap production with only one set. But it IS fun, with cute boys running around in swimming trunks and wet suits, hot ladies and men of a slightly older generation as the leads, and fab Abba songs from when we were young and callow. Alas, we’re not young anymore! Mamma Mia never takes itself seriously which is one of the reasons it works. Ford Center/Oriental through Sept. 27; (312) 902-1400; $37-$78.