Back in the 70's my wife and I used to go to a XXX rated movie house. I tried to convince her to give me head during the movie but she was hesitant until we were seated next to a couple where the wife/GF had her skirt up to her waist and was sitting on her partner obviously fucking his brains out. After that my wife not only went down on me but usually finger-fucked herself and got off during the show, much to the pleasure of those around her.