look up any word, like trill:
 
1.
a sign or warning of any impending danger, disaster or doom
when my gf called me up that day and gave me the "we need to talk" line, a red flag obviously came up and I figured I'd soon be on the outs with her.
by Bungalow Bill November 18, 2006
 
2.
Stopping what you're doing because because something has made the environment unsafe. Derived from the racing flag that is used to stop a race because of unsafe conditions.
"We're red-flagged at this gas station because it's snowing too hard for us to be able to go on."
by D2RCR January 31, 2004
 
3.
The traditional color flag of the Blood gang
Dave:Look at that Krab with his blue shit!
Ed:Yeah us Bloodz wear that red flag til we die!
by Jasmine C tha G January 07, 2006
 
4.
1) Traditional symbol of socialist resistance.

2) in an Orwellian reversal, also the song sung by Blair and his cronies at Labour Party Conference
Red Flag (song), Blair version:

We'll suck up to the ruling class
We'll fuck the workers up the ass
And just to show that we're sincere
We'll sing the Red Flag once a year.
by annoyed anarchist May 28, 2004
 
5.
1. a warning sign

2. subject to a warning
A funnel cloud is a red flag for the formation of a tornado.
by The Return of Light Joker October 15, 2009
 
6.
term used to cut someone off from drinking for the night.
(girl stumbles around and ends up puking on someone's shoes at a party)
Some Dude: YO, That bitch is red flagged! Get her outta here.
by meeeeecrock January 31, 2007
 
7.
the flag of no quarter. used by pirates, the red flag was flown from the pirate ship when a merchant ship pirates were targeting offered resistance.

no quarter means that the pirates intended to take no prisoners.
some buster smoke up all my smokin' weed.

show him the red flag.

no quarter for dat sucka!
by zen November 30, 2006