When a woman (or possibly a man) wears a button-down shirt that is a little too tight, resulting in the fabric straining at the buttons, and forming a gap. This allows friends, family, and/or the general public to have a glimpse of your side-boob.
"Oh man! That girl should really put a sweater on."

"Why?"

"Because she's totally gap-flashin' the entire coffee shop!"
by america's cynic January 27, 2010
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could outrun flash is a metaphor meaning super fast.
If something could outrun flash in a race it means that they are super fast.
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When a girl flashes her pubes to another individual
When i was pulling down my pants, i accidentally carpet flashed my friend.
by daflashers April 01, 2015
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On 4/20, in support of marijuana legalization flash a friend (can be done by male or female).
I just saw 2 topless women on 420 flash a friend day in support of legalization!
by SubwayJered April 20, 2019
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