The force of physics enacted upon ones arm after fist pumping for an extended period of time that causes one to continue fist pumping for a long period of time after. Can last anywhere from hours to days depending on the severity of the fist pump.
Artur: Why are you still fist pumping, its been days since that party ended.
Joe: Can't bro, I've got fist pump momentum.
Joe: Can't bro, I've got fist pump momentum.
by JoeBroFoSho September 19, 2011