A man goes to a whore house..

On the wall you can pick diffent numbers for different sexual acts.. Of course he picks #69.. She takes him back, they start 69ing... A minute or so in she farts right in his face.. He waves it off, continues on, all of a sudden, she farts again!.. A minute later she asks "how you liking it?"... He says "it's pretty good but I don't think I can take 67 more of those".