When you're walking along and you suddenly let go of every muscle in your body, making it look like you died instantly. Works best next to a pool or on the beach.
Watch me walk along the edge of this pool, I'm gonna instadeath into it.
by GGK78 May 16, 2013
1 more definition
An excessive concentration of something.
Damn this coffee is strong enough to cause instadeath.
by Sara Snider October 11, 2007