Depending on his definition of "Happening", he could try the following clubs...
Rock and Roll Beach Club - Music, Video Games, Pizza
Motion (used to be Wildhorse Saloon)- Current top hits, lots of strobe lights and loud music VERY LOUD (might be 21+)
8TRAX - Don't know much about this one, but I think it currently plays 70's music
There are other clubs he could try (Pleasure Island Jazz Company, Adventurer's Club, Comedy Warehouse), but I don't necessarily think they would qualify as "happening" in his eyes.
Unfortunately, the other two clubs (Mannequins and BET Soundstage Club) that he might be interested in are 21+
HELP! 
it's all about the mouse! 
