a girl or guy who has an S.T.D or S.T.I. meaning: dont have intercorse with her.
She's hot but she's red flagged.
by morphine lips June 26, 2006
Verb: The state of a book or magazine after someone brings it into the bathroom with them, generally when dropping a deuce.
Dude, don't put that gun magazine back on my desk, you just red flagged it.
by Captain ASDF December 18, 2008