descoyuntar

To dislocate a joint (descoyuntarse un hombro), and, colloquially, descoyuntarse de risa — to laugh so hard your body seems to come apart at the joints, one of several exaggerated Spanish idioms for intense laughter alongside desternillarse and morirse de risa.

• Se descoyuntó el hombro al caer de la bicicleta. — He dislocated his shoulder falling off the bike.
• Nos descoyuntamos de risa viendo esa película. — We laughed ourselves silly watching that movie.
• El médico le recolocó el hueso descoyuntado. — The doctor reset the dislocated bone.

Learners sometimes take descoyuntarse de risa too literally — it's a stock hyperbolic idiom for laughing hard, not a real physical injury, so don't undersell or overexplain it as if it were medical.