From sports lingo, a shat trick is pooping 3 times in one day.
That Mexican I ate last night didn't sit well. Counting the cock a doodle poo and the two times at work, I got a shat trick today.
When an individual takes 3 shits in a single day. Like a hat trick, it is very difficult to achieve but very satisfying when finally done.
Steve: Yo Matt, I finally took 3 shits in one day!
Matt: HOLY S#%T that's a Shat trick!
Steve: Matt I have finally achieved a Shat Trick!
Matt: Damn, I was so close last night but couldn't push the third one out!