What's left to say? Unless you've been hermiting on Mars, chances are you've seen Mamma Mia! on stage, or heard the score, or seen the movie. Or all of the above. Multiple times. The cheesy touring production at the Academy of Music was my third MM, not counting the delish movie. As my date for the evening said, when he heard my teeth grinding: "It is what it is." He's deep, this guy.

The plot revolves around Sophie - played on opening night by understudy Stephanie Barnum - a young woman who lives on a Greek island with her mother, Donna (Michelle Dawson, who seems to be the only cast member who can sing and act). When she reads her mother's diary to try to discover who her father is, there turns out to be three candidates, all of whom she invites to her wedding.

The charmlessness of the three potential dads stands out in this lackluster cast: British Harry (Michael Aaron Lindner), Australian Bill (played by understudy Vincent Corazza, who changes him to American (accent difficulties?), and the true love of Donna's life, Sam (John Hemphill, who seems unable to figure out what to do with his hands while singing).

Everybody sexualizes absolutely everything, but it's not the sexiness that's embarrassing, it's the smarmy vulgarity. Similarly blatant is the music: The orchestra is so loud that even the amplified voices are nearly drowned out.

The show, with its ABBA songs - "Dancing Queen," "Honey Honey," "Money, Money, Money," "The Name of the Game," "Take a Chance on Me," to name the best known, plus, of course, the title song - has fans worldwide, and its anthropology amazes me: It has been seen by more than 40 million people and has grossed more than $2 billion. There are foreign-language productions in Japanese, Korean, Dutch, Flemish, Russian, and Norwegian, to mention just a few.

The audience contained many little girls, some young enough to need booster seats. What could they have understood of the plot? Or the lap dances?

Then there were the women embracing each other, weeping in their enjoyment, and others heatedly debating whether a song was omitted from the movie, which they had just watched the night before. And people lined up 10 deep in the lobby to buy the merchandise.

Well, it is what it is.

Mamma Mia!

Through Sunday at the Academy of Music, Broad and Locust Streets. Tickets $28-$82.50. Information 215-731-3333 or www.kimmelcenter.org/broadway.