Similar to dropping a deuce, which means to move your bowels; dropping 20s means the same thing, the only difference is that it is 10 times worse. Explosive diarrhea could be considered a 20.
"Hey John, I really gotta go drop this 20."

"Huh? Drop a 20?" replies Stan.

"Yeah my dude, I feel like I gotta drop 10 deuces so make way!!!!"

"Oh I get it, dropping 20s." chuckles Stan.
by mytchiemitch October 30, 2009
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