My bonny lies over the ocean

Sing (or teach):

One step at a time (!), invite singers to:
 * stand up or sit down every time they sing a word starting with a B
 * salute every time they sing a word starting with an M
 * clap every time they sing a word containing an O

Then combine two or even all three. Last singer not to collapse in a fit of giggles (kids) or fury (adults) gets a lolly.