Skeleton's Roofing Material

Okay, listen up, you genius. You thought it was some kind of bone-related roofing material, didn't you? But no, it's a pun. You see, a 'shin' is a bone in your leg, and a 'gull' is a bird. 'Shin-gulls' sounds like 'shingles,' which is the stuff you put on a roof. So, it's a silly play on words, kinda like your attempts at comedy. You're welcome.