Pain in the butt after being rear ended? No double entendre intended (ya pervs) - I mean if you've literally got pain in the butt after a traffic accident, then perhaps you've got a case of Popeye Butt:
... while having a butt like Popeye’s bicep sounds even worse, it’s actually a medical first, according to some scientists who, after diagnosing the first medically-described butt-muscle rupture, gave the condition the official name of “popeye gluteus.” [...]
“Popeye gluteus” was agreed upon not because the bruising resembled a popeye-like black eye, but because the muscle deformity “was like a prominence that ‘bunched up’ when he tensed his buttock muscle,” Wood said in an email. The photographs in their study didn’t adequately capture the injury’s protruding shape, and the name so supposed to tip off that the muscle actually popped up from its usual position. The name also refers to Popeye biceps, a known injury in which shoulders rupture and bicep muscles bunch up, and Wood’s group just applied the same term to a ruptured buttock.”We thought that describing the deformity as a ‘popeye gluteus’ would make people think of the ‘popeye biceps‘ deformity in biceps rupture,” adds Wood.