Possible Clues:

• Toots and thwacks
• An Evening Standard review calls Michael Frayn’s ____ Off “the funniest farce ever written”
• Snap, crackle and pop, for three
• Sounds, rackets
• __ Off, comedy by Michael Frayn
• Sounds unwanted?
• Auditory inputs
• Click and clack
• Sounds hooters, the first person must go inside
• Clangs and bangs