To have poisoned insects or critters. Derived from a trademark named insecticide.
Yolanda blackflagged her crabs with lindane.
by harry flashman July 10, 2003
to do something fucked up or wrong. Usually followed by someone waving a small black flag and the words "You done fucked up, son"
Tynise black flagged when she texted the wrong person. Twice.
by DistructiveHamster September 15, 2013
Getting really wasted and fucking up all night long usually with a big group of friends.
Mark was chugging four locos when he got up and shoved Christian hard on the toilet.He was so black flagged.
by Myersgirl November 02, 2013