1. (noun) foolish or senseless behavior

• craziness
• folly
• foolery
• indulgence
• lunacy

1. (noun) foolish or senseless behavior

• buffoonery
• clowning
• frivolity
• harlequinade
• japery
• prank
• meshugaas
• mishegaas
• mishegoss

1. (noun) foolish or senseless behavior

• caper
• frolic
• gambol
• play
• romp

1. (noun) foolish or senseless behavior

• arse around
• fool
• fool around
• horse around
• crazy
• crazy
• half-baked
• screwball
• softheaded
• lunatic
• moonstruck