Define Rst Meaning

I read an RST where Nick Stokes and Greg Sanders have sex up against a fridge.

some people say it like this wtf instead of abcdefg hijk lmnop qrs tuv wxyz
abcdefg hijk lmn opq rst uvw xyz is not normal

person1: You don't have to worry about that.
person2: rsts!

“Let’s ksa & rst tonight!”