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The notion of Bumblasting is dipping your ass on to someone's face as a show of mockery or irritance.

The perception is in relation to "Tea Bagging" where as instead your aim is for your bottom (or a character in a video game) to connect to a body's face whether up or down from the floor.
Huzzah ha ha, reek the wrath of my "Bumblasting" you noob spawn killer.

I had to "Bumblast" my mate's face who slept over yesterday due to his ever increased snoring.

by SquirrelPower September 14, 2008
anal penetration
His boyfriend enjoys a good bum blast with extra lubricant.
by BR2112 May 20, 2009