1 definition by Fuse fan
The simultaneous facial and sphincter clench just before a fart is released. 'Flench' is therefore a fusing of the key words 'fart' and 'clench'.
Mary: "My goodness can you smell that? Who farted?"
Joe: "It was Mark, I saw him flench right before the smell hit"
Joe: "It was Mark, I saw him flench right before the smell hit"
by Fuse fan February 27, 2010