harlem airshaft
Once the anus has stretched to its maximum capacity during anal sex, the penis is pulled out, leaving the anus open. The receiving man/woman/goat then flatulates, but since there is no skin to vibrate and produce a normal flatulent sound only the sound of rushing air is heard. Named after a Duke Ellington song.
"When Jay pulled that piece out of Marty's assbag, Marty's piece was spread so wide that when he farted it was a Harlem Airshaft."