A male greeting. Two gentlemen see each other in public and give each other a hearty pelvic thrust. They're testicles smack together creating a bag bump
Hey man, I saw dude yesterday and he gave me a vicious bag bump. My balls are still hurting.
The two ticks up in volume you do on a tv, computer, or other audio source when you're eating a crunchyfood so you can still hear it.
"I was watching The Big Bang Theory and opened a bag of pretzels, so I had to crunch bump the volume."
"I know exactly what you mean! But dude, I didn't know you watched The Big Bang Theory. We can't be friends anymore, sorry."