On a powder keg

Oblivious to upcoming disaster. Waiting around seemingly unaware that nothing can go right where you are now.

“You may not think it at the time, but you’d be sitting on a powder keg if you drove home any way but sober.”

Columbian Powder Keg

When you put cocaine in someone's asshole and wait for them to fart a coke-cloud. Once the cloud has formed, you snort as much cocaine as you can/want.

Eric: Hey you wanna do a Columbian Powder Keg with me?
john: Sure, whos gonna be the cannon first?