Is caused when one takes a messy shit and doesn't remove all the dirty residue. After walking around your ass cheeks become chaffed. Its the worst on a hot summer's day. This can also happen to male when ramming a persons unclean ass.
John took an explosive dump as soon as we got to Amusement Park. At the end of the day he looked like someone had shoved a 12 foot dick in his ass. He was suffering from the scat scratch.
Guy to Friend- "Dude, I nailed Betty in the ass the other night. I don't think she didn't wiped good enough. my dick has a huge scat scratch.