Because "pump" would've been much worse.
Note: Extra, behind-the-scenes, not-posted-on-Facebook photos included.
"You know I can't make a fist, right?"
"Fine, but like I said before, I can't make a fist."
(Note: Foamy drool on floor and missing drywall left in for trashy effect.)
"OH YEAH, WELL I'LL SHOW YOU WHERE YOU CAN PUMP THAT FIST!"
Tune in next Wednesday when I rhyme "hump" with...??? ☺