Skin Flick Music!

A trumpeter is hired to play two solos in a movie. After the sessions he is paid handsomely and promised by the director that he will be notified when the movie is released to the public. 

Three months later, he receives a notice that the movie will make its debut in Times Square at a porno house. The musician enters the theatre wearing a dark raincoat and shades. Unaccustomed to porno flicks, he sits in the last row next to an elderly couple. 

The film has explicit sex scenes: oral intercourse, anal intercourse, golden showers, sado-masochism and near the end a dog has intercourse with the leading female character. 

The musician who is immensely embarrassed turns to the elderly couple and whispers, "I wrote the score and I just came to hear the music", to which the elderly woman whispers in reply, "We just came to see our dog."