Blue flag

Generally a blue bandana, most commonly used by Los Angeles street gang known as the Crips.

"You see the blue flag in his left pocket? That's a Crip."

Blue flag by VQC BK December 18, 2009

Blue Nun

A brand of German wine which is considered "tacky and dated".

Alan Partridge:
"Yeah I'll Just have half a bottle of Blue Nun"

Blue Nun by Bwanana January 18, 2008

Blue Bolt 

In Dungeons and Dragons a Blue Bolt is when a players character is suddenly struck by a bolt of lightning that ignores all ArmorClass, Spell Resistance, or any form of resistance. There is no avoiding, dodging, resisting, or surviving or resurrection from a hit by a Blue Bolt. A Blue Bolt can be summoned anywhere anytime without reason by the DM and it is traditional for the DM to first ask for a players character sheet, promptly tear it in half and pronounce that the player was hit by a Blue Bolt.

"Dude last night Ben's character was hit by a blue bolt. He is soo bummed"
"Ya, I heard he ate the last piece of pizza and the DM was super pissed. Ben got what was coming to him"
"For sure"

Blue Bolt by Rytherix January 28, 2009

Blue Whaling 

To absorb, accept and consume any and all exterior elements; in the same form as a blue whale feeds by opening its mouth and swimming, capturing any organism that is in its way.

Esteban is blue whaling on girls tonight. (meaning he will pursue, date, sleep with, any female that comes his way.)

Blue Whaling by Ahab69 May 12, 2015

Blue Madonna

An untouchable woman with a captivating orea, beautiful or great in height, secretive and balanced.

Someone must have sent me to heaven
Blue madonna down by the pool

Blue Madonna by Blue Madonna June 16, 2018

Blue Anon 

A leftist conspiracy ideology so offensively true they had it removed from a fake slang dictionary

All these lefties offended bring called out for being part of Blue Anon because it's true.

Blue Anon by Theorist84 March 7, 2021

blue box 

A tone generator built and used by phone phreaks during the 70s to illegally obtain free telephone service by synthesizing audio dial tones used for controlling switching stations.

The infamous hacker icon Captain Crunch helped to popularize usage of the blue box in the 70s, making AT&T's long distance phone service affordable for the masses.

blue box by CaptainKrunch March 6, 2008