When the production team making a show can't afford a real band to act as a collective Celebrity Star or Special Guest, they just build one out of whatever actors Central Casting has handy, and pretend that they are the hot new thing in the world of the program. "Evidence" of their talent is either non-existent, or provided by anonymous studio musicians to whose performance the actors lipsync. (Rarely does the Fake Band actually have real musicians in it, save for the truly postmodern moments when a real band is masquerading as a Fake Band -- which has been known to happen.)
In a few examples, the Fake Band actually releases real music, usually as a shameless media tie-in. For a really shameless tie-in, or if a developer wants to throw in a Shout-Out, get the music into Guitar Hero or Rock Band.