masturbating in the bathroom while your roommates are out and are unsure of when they'll return; IE, maturbating while home alone.
Pun on the word "caulking" (pronounced "call-king"), the rubbery silicone sealant around
tubs and sinks.
roommate: What the hell were you doing in the
bathroom when I got home? You were in there for a while.
deviant: Oh just Macaulay Caulking the bathtub tiles... you didn't leave a note so I didn't know when you'd be home.
roomate:
gross