Punk musicians usually serve three basic purposes. They entertain the teeming teen masses. They titillate adolescent libidos. And, oh yes, occasionally they make decent music.

In the case of Cheap Trick -- to out of three ain't bad.

Their show last night at McDonough Arena was a teeny-bopper's delight from the first stage pose to the last. Guitarist Rick Nielsen vamped, tramped and canted up, throwing picks, guitars and mike stands about and generally wreaking witty mayhem. Singer Robin Zander was planted at center stage, his golden locks flowing to his shoulders. When he shook his hair, a thousand screaming girls rose to their feet. After one song, he unfurled a banner that read, "Cheap Trick -- Sex Gods of the '80s." The crowd whistled and yelled.

Musically, the group was content to borrow from the heavy-metal sound of the '60s and '70s. They spewed out cliched blues and solos and thumping beats, all at a volume that threatened to produce temporary hearing loss.

To be fair, the members of Cheap Trick were lively performers. And performing, not playing music, was what their show was all about. The teens went away satiated. The group made a dollar or two.Everyone was happy.