Anytime you (or someone else) is trying to look casual but are secretly flexing in a picture or pose to make your muscles (usually arms) look bigger. This includes but not limited to, a hidden clinched fist to make your biceps look bigger, and also having your arms pressed against your body to make them look bigger.
Look at that guy, who is he trying to kid. His arms are not that big. He's just doing THE SILENT FLEX.
by ColeManND87 January 16, 2015
 Get the The Silent Flexmug.
Get the The Silent Flexmug. by Ggbandz May 19, 2018
 Get the old flexmug.
Get the old flexmug. To do more work than nesscary, like when someone flexes their  back more than needed to do something.
This phrase is usually assoicated with doing with doing extra credit homework or taking 2 hours to work that can easily performed in 30 mins, generally all schoolwork that geeks and nerds do.
This phrase is usually assoicated with doing with doing extra credit homework or taking 2 hours to work that can easily performed in 30 mins, generally all schoolwork that geeks and nerds do.
Me:How many of pages of coursework you do? I did 9, font size 14
Zubair: Man I was up till 3 in the morning and did 33 pages, font size 10.
Me: Your long flex dude.
Zubair: Man I was up till 3 in the morning and did 33 pages, font size 10.
Me: Your long flex dude.
by Carl Anka April 12, 2006
 Get the long flexmug.
Get the long flexmug. by heartthatmaryjane April 5, 2011
 Get the weed-flexmug.
Get the weed-flexmug. A creation by the almighty god Phil Swift who can patch, bond, seal, and repair with no effort at all. It is his gift to us mortals to repair our foolish mistakes. Don’t try making it at home, because it is a creation by a GOD, not a HUMAN. Only the most worthy people are chosen to own it. Without Flex Tape, we would not exist.
John: “Phil Swift appeared in front of me and gave me a roll of Flex Tape yesterday!”
Caden: “You should be glad, he has chosen you as a worthy bearer of that supernatural gift.
Caden: “You should be glad, he has chosen you as a worthy bearer of that supernatural gift.
by Big Ol' Boy April 19, 2019
 Get the Flex Tapemug.
Get the Flex Tapemug. The retractable fluids of Phil Swift
by Cactii  November 13, 2018
 Get the Flex Tapemug.
Get the Flex Tapemug. When you think you’re better than someone else by posting a picture on Instagram acting like you got it like that but really you don’t.
by Paul Pistone  May 25, 2018
 Get the Instagram flexingmug.
Get the Instagram flexingmug.