back-splatter

Noun. The high-velocity pattern made by liquid fecal matter on the back of the toilet above the waterline. This pattern is formed when one has an uncontrolled evacuation of the bowels as he or she is in the process of sitting down and is still in a leaning-forward position. Because the movement associated with this phenomenon is usually time-consuming, the resulting back-splatter typically dries and will not come off when the toilet if flushed. Back-splatter usually lasts until physically removed with a brush and Comet.

when someone pulls out after anal sex
and splatters semen on your backside.

The line of mud pasted onto ones back, after one has been riding a bike through said mud, thus producing the upward lift of said mud, from the circular motion of the wheels on said bike in motion.
Said word was created after observation of competative bikers training in the rain who stopped at a diner and all looked like skunks with their enormus examples of back-splatter in its perfect state.

The act of vigorously thrusting your shaft deep into a girl on her period, causing blood to splatter over your genitals and belly.

When the male in an instance of intercourse using the position from behind -doggy style in laymans terms- defecates into his hand and in one motion, "splatters" the feces on her "back". Hence, "Splatter back".