A Joke

My friend told me this joke today:

A guy gets experimental penis-enlargement surgery and goes out for dinner with a date (presumably after he's had time to heal). Halfway through the meal, an elephant trunk comes up from between the guy's legs and snatches a bread roll off the table. To his date's fascination, he explains the avant-garde procedure. Warming to the idea, she asks him to do it again. "I would," he replies, "I just don't know if I can fit another roll up my ass."