Musical Improv Games - Showstopper

Good for:

High-kicking Broadway madness and commitment

Two or three players start a very dull scene
At a signal from someone in the wings, one of the characters breaks into a fully choreographed singing and dancing routine based on the last thing they said - even if it was "Smell my cheese".
Give it a big finish
Melt back into the dull scene and await the next outburst
Not to be confused with "Showstoppers! An Improvised Musical" which is a West End fully improvised musical (starring our very own Heather) as opposed to a silly exercise lasting a minute or two.

The cue for the next showstopper could just be the music starting to play
As one of the characters in the scene, make a choice - can you 'hear' the soloist? Can you react to this, or just carry on doing some object work in the background?
On the last one maybe everyone is sucked in to a big jazz hands finish.