An ass attack is when you are feeling completely normal without the feeling of having to take a shit. Then all of a sudden out of nowhere you have to shit and shit BAD!! You pretty much have less than one minute to find a toilet. It can happen anytime or anywhere.
I was standing in my kitchen feeling completely normal making dinner then all of a sudden I had an Ass Attack, so I ran to the bathroom and pulled my pants down just in time to make it in the toilet.