A flash grenade is a girl who, due to her mastery of the art of deception, appears NOT to be a grenade. She operates similarly to the M84 flashbang issued by the United States army in the sense that it subdues its target in order to trap it, but doesn't kill it so that it can be taken advantage of in ways that require a live body. (Sort of like how some parasites will inject an anti-inflammatory into it's host.) It is only after the victim wakes up that he realizes that he actually hooked up with a grenade.

Flash grenades can be identified easily if one pays attention to the right details. Extremely tan, tons of jewelry, skanky outfit, and caked on make-up are clues that you may be dealing with a flash grenade.

Flash grenades become much better at being flash grenades with each alcoholic drink consumed by the target.
"I don't remember this ugly girl from last night, how'd I get in her bed?" (she was a flash grenade, that's how)
by sammymoto August 28, 2010
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When a Female squirts into a Male's mouth, then the male quickly spits it onto the Female's face, giving her a grenade-like splatter all over her.
We had an amazing time at the party last night! Some girl and I had sex, and I ended up giving her an unexpected Flash Grenade.
by The Dichter October 16, 2015
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