There are many ancient varieties of this pun. This newer version was posted by Kelly Fitzpatrick in alt.callahans.

Today’s Pathetic Daily Snooze prominently features an advertisement showing the smiling mug of Bob Walker, a thirty year veteran of the horse slaughtering industry. Bob had never considered the possibilities of equine consumption until the recent controversy regarding the sale of mad-beef from the English countryside. Now, though, he is seen halfway ’round the globe, hoisting a lovely haunch of British ex-Racing … Read the rest...