When one is so drunk, one is willing to place a rocket-like firecracker between one's butt cheeks and fire it off.
"What ho, stout Yeoman? Might I infer by thine Countenance that thou hast been tempted by The Drink?"
"Verily! In celebrating somewhat belatedly Her Royal Highness' Golden Jubilee, my Compatriots and I didst become so emboldened as to consequently suffer the following Reproach of a fine and honest Gentlewoman: 'Ye Gods, you Vagabonds, but you have become ass-rocketdrunk!'"
Violent, gut wrenching defication. So violent that you have to strap on to the toilet not to be launched into orbit. Much gas is expelled along with, well, you know... the other stuff...
1. Shane suffered from IBS, so everyday after lunch he would have an Ass Rocket.
2. Wow! That Ass Rocket was so bad I had to strap in to keep from being launched through the roof!
Similar to the idiom, "Wear Your Heart On Your Sleeve" but instead of expressing your emotions freely, you (or someone else) show how much of an asshole you are.
Cal: Yeah, so I punched him in the face for taking the last slice of pizza.
Rudi: It was his birthday, assjacket.