skin magazine

Stephen KingのThe Running Manを読んでいます。
He tossed the Ogden Grassner glasses in the glove box and drove out, waving noncommittally at the gate. The boy barely looked up from the skin magazine he was reading.
"skin magazine" は初めて見る単語ですが、エロ雑誌ではないかと推測できます。辞書で確認します。
・Collins Dictionary: a magazine containing pornographic images
・Urban Dictionary: A Copy of pornographic literature; Porn, Pornography, Adult literature; Porn and Porno are informal examples.: I just found some Skin Magazines under Tommy's bed.
当たりでした。