Uncle Sledge is Howard's uncle, who has never been properly seen in the show.
Description[]
He has never made a full appearance on the show, thus his physical appearance and backstory is largely unknown. Except for the fact that he appears to have a criminal history and may be a con artist, indicated by the limited information mentioned about him. Howard also appears to have a fondness for his uncle, given by how he thanked him for giving a ride, and apologized for making a mess in his car, as well as smiling while talking about him.
History[]
He first appears in, "Julian's Birthday Surprise", he dropped Howard off at the Magic Funporium and then promptly drove off as he was in the middle a car chase with the police.
He is then mentioned by Howard in, "Shoot First, Ask Question Laser." He is used as a metaphor for a scam, as Howard puts it, "pretending to have tickets, but you really don't" or "Pulling an Uncle Sledge" which basically means, trying to get something from a person by pretending to have an object that the person wants, that they are willing to trade or bet on, but the scammer doesn't actually possess such an item."
Randy, who is apparently aware of Sledge's history follows up by asking how his uncle has been doing, to which Howard response by telling him that he recently acquired his yard privileges again. Implying that Sledge had already been arrested by the police likely in, "Julian's Birthday Surprise" and is currently in prison.