: playful or foolish behavior
"Most only remember [Bobby Valentine] for his dugout tomfoolery as manager of the New York Mets, when – after being ejected in the 12th inning of a game against the Blue Jays – Valentine returned to the bench wearing a fake mustache." – Zach Drucker, The Tufts Daily, December 4, 2011
About the Word:
Tomfoolery comes from Thome Fole, a name that Middle English speakers applied to anyone they considered a half-wit. Thome was a nickname for "Thomas" and fole meant simply "fool."