Its when you fuck someone so hard, that the impact of your bodies against each others makes a loud thunderous sound
Timmy: Suzy and I thunder banged last night and the neighbors got freaked out, they thought there was a storm coming.
Ben: THAT LOUD NOISE WAS YOU TWO?
When a very skinny chinese male humps a skinny chinese female non stop until there is bleeding. After that the male puts his ballsack in her face and she sucks the balls until it hurts.
Zane: Heyy Scottie lets have dinner and mookie bang.
Scottie:Dude that's sounds a bit gay .How do yoy spell it.
Zane: It doesn't matter how you spell it and it's not gay . It mean let's eat and talk a MOCHIE BANG!
Scottie:oh okay let's bang!