An old couple were in bed one morning. (An old joke my dad used to tell)

And like every other morning for the past 40 years, the old man lets rip a ground-shaking fart. His wife, growing tired of this, turns to him and says

"One day you're going to fart so hard you'll shit out your guts!", to which the old man laughs.

A few weeks later, the wife had got up especially early to prepare the sunday roast. As she was about to throw away the giblets, she had an idea and crept up to the bedroom where her husband was still fast asleep, and quietly placed the giblets between his legs.
Half an hour goes by before she hears a scream from upstairs and a few minutes later her clearly shaken husband rushes into the kitchen.

"Whatever is the matter dear?" the wife asks, stifling a laugh.

"You were right!", he replies. "I farted so hard I shit my guts out! But by Gods good grace and these two fingers I managed to shove them back in there!"