The sudden and alarming hissy fit that grown men have when confronted with information that they don't like, or when asked to do something that they don't want to do. Asking for some attention to be paid to you instead of a games console, for instance, will almost always result in a man strop. Likewise, the dreadful crime of informing him that he has behaved like a twat will be punishable by a full on man strop.
"I sked him to stop playing that thing for 5 minutes and listen to me, and he threw the controller down and stormed around in a total man strop"
"Grow up, you fucking baby, stop throwing such a man strop!"