Melmacians die at age 650 (unless, presumably, there is an accident of some kind). Melmacian funeral customs involve a celebration and are considered a very happy time. The embalming process involves the use of various fruit juices. Funeral goers dress as vegetables.
(PLEASE NOTE: The syndicated/DVD version of the episode "We're So Sorry, Uncle Albert," cuts ALF's explanation of the Melmacian custom of celebrating a person's life at their memorial. Tragically, without this incredibly important piece of information, ALF's motives for throwing the party at Uncle Albert's untimely death seem extremely self-centered and ghoulish.)