bum yawn

A slow, tired and usually involuntary fart continually emitted by sphincters of the clientèle of the Cherry Orchard in Chester. Such yawns are commonly encountered after a plate of egg mayonnaise sandwiches and mini pork pies has been circulated.

"Jesus H Christ, is there a body under the floor boards in here? That smell is enough to choke a dung fly."

"that'll be john, he's just had a bum yawn"