when you attempt a fist bump, but your friend does a high five ending up in a half fist bump, half high five.
hey man what's up? "fwump!"
by JERALDtc May 20, 2013
The sound a forceful poo deposit causes when it makes contact with the water in a toilet.
I squatted down and then fwump! my ass was soaked after a tsunamic reverse flush.
by mrs_equator September 23, 2006