Happy to bring forth noob quotes for your entertainment *takes a deep bow* ^_^
But i've seen people using the jump key (plain bound bhop) and still managed to push them back with a couple m4 bursts to the back of the head. However, I've seen zombies take a running jump at say the bookshelf spot on mini room and despite a TEAM of humans hitting the zombie with autoshotty, my m4, and your pump in the face, he goes NOWHERE. I'm not saying normal bound bhop doesn't help in getting in crouch spots, but typically if you hit the head, you still push them back (minus the dreaded deformed which is the bane of all crouch spots

).