When some one tries to be cool by telling you something, but you don't give damn, that's what you say.
Looser kid: hey! I just prestiged in call of duty!
You: cool bro,
Random friend: you have no friends.
You: cool bro,
Random friend: you have no friends.
by !young beaner!! September 18, 2010

The phrase of choice of a very loud Armenian male population, especially from Glendale, CA when they disapprove of anything not to thier satisfaction. Normally said in a very loud, booming voice with a rolling 'rrr'. This phrase is used mostly in driving situations where the all too perfect Armenian driving style has been disrupted in some way.
Shouting from his driver' side window - "Hey BRO! Not Cool Bro! Why you make lane change my lane when you KNOW I coming BRO!?? NOT COOL BRO!!".
by Glendale, California November 09, 2011

What you sarcastically tell someone when they're saying something cool yet uninteresting. Abbreviation= TCB.
Cody was telling Susie a story and instead of telling him to keep going on she said that's cool bro instead of cool story bro.
by BroTime April 16, 2014

Person One: "(Tells extremely lengthy anecdote about his grandma knitting him a sweater)"
Person Two: Cool bro, story
Person Two: Cool bro, story
by Tammy McShammerson May 02, 2010

The coolest group ever (360 dabs everywhere). When in the group you will drown in pussy and become the gods of poo.
by THE AMERICAN GEEZA June 27, 2020

You: (Just told a story or event that bores your friend)
Friend: Cool Story Bro (CSB)
You: Too Cool Bro (TCB)
Friend: Cool Story Bro (CSB)
You: Too Cool Bro (TCB)
by Hariras. T November 27, 2011
