From an Old English word meaning "wander about idly," a scrounger is one who gets only what he needs, and only when he needs it, by foraging, scavenging, or cadging. Although it's become synonymous with sponging, scrounging is actually a noble art which combines - as the word itself seems to do - sauntering, lounging, and creativity. See: BEGGAR, BUM, CADGER, SAUNTER, SCAMP.

someone who mooches or cadges (tries to get something free)

an important and valued person in prison camps, jails, and college dormatories