Wrap Master Squirrel is, as the name implies, a rapping squirrel. His name is an environmental spin on the moniker "rap master."
Introduced by a voice-over announcer, he suddenly appears in the Park in Episode 3427 of Sesame Street. He performs a rap about picking up litter, which is in fact the song "Litter Rap." Footage from that insert is intercut with the rapping squirrel at a stump and Big Bird and the kids cleaning up the park.