An event that is the result of one becoming very excited (be it positive or negative excitement) whilst typing, resulting in one sending a random (usually long) string of random letters and/or characters caused by randomly mashing buttons on one's keyboard--hence the name. These are a common occurance in online conversations (i.e. IMing, Facebook, ect.) and text messages.
Example 1 (negative anger/frustration):
Kaitlyn: OMG, L just died on Death Note!
Ryan: bdjbsdbjhsdbdhdb OMG NO. ;A;
Kaitlyn: ......it's just a show, no need in keymashing on me.
Example 2 (positive excitement):
Damon: Yobanashi Deceive came out today!
Samantha: kmklmoninnninipiihj''mk I MUST HAVE IT!!!!! <3
Damon: O-o Judging by that keymashing you were doing, I should say so...
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