A portmanteau of the words "shit" and "strangle" (a la "slithy" or "mimsy") meaning to strangle someone with such force, you poop your pants.
"Remember that German girl I met at the bar last night? When we got to her dorm room, she wanted me to shrangle her..."
"Well, did you?"
"Fuck yeah I did! But I straight up destroyed the sheets on her bed..."