Ass-ter Shock 

The shock that one gets while leaning forward to wipe after taking a dump and finding that the automatic flush thinks you have vacated ..... leaving a soggy ass.

Holy shit - that always happens. Now my ass is wet and shitty - I hate Ass-ter Shock

Or...

Why is that guys pants so wet? Must have been a victim of Ass-ter Shock

Ass-ter Shock by The Brown Fox January 16, 2013

asstershock 

After ripping an ass explosion, the small fart(s) that come after it. Can often be smellier than the big one.

Keith kept farting through the whole damn movie, but his asstershocks were worse.

asstershock by bb+af June 29, 2010

Asstershock 

when You take a shit so massive, it backed up a bunch of gas. Asstershock is those farts that explode out your ass after you shit.

1: Bobby had gas pains in his stomach because the shit that was about to be expelled from his ass was blocking all of it up. He then had asstershock for an hour.

Asstershock by Smash_the_Pumpkins May 30, 2019