If you’re feeling a little feisty this Sunday, bring your pillow to Bergen Place (that triangular park with the mural), on the Market St. side, between Ballard Ave. and 22nd. “Standard flash mob format,” reads the email that’s flying around. “Conceal your pillow, look busy. Listen for the whistle.” It’ll blow at 2:22 p.m., which is your cue to start swinging for five minutes. “When you hear the second whistle, stop fighting and walk away like nothing happened.”

This is what a flash mob pillow fight looked like in Boston. Arrrgh!