Walton Goggins uses an 80-year-old body double for his nude scenes.
When the character of Baby Billy is introduced, he climbs out of the bath and puts on a housecoat. The housecoat closely resembles the "Technicolor Dreamcoat" from the Andrew Lloyd Webber musical Joseph and the Technicolor Dreamcoat which chronicles the biblical story of Joseph.
Walton Goggins' very first scene in the show features a full frontal. Goggins admitted in an interview that his "dick double" was an 80-year-old man. While Goggins was open to doing the scene himself, he is only 48, while his character is supposed to be 70.
This is Walton Goggins' second collaboration with Danny McBride, having previously worked with him on Vice Principals (2016).