Per my two minutes of online research, this is the origin of the phrase "Pull One's Leg":
"When you pull a person's leg you are spoofing or making fun of him, usually in a good-humored way. But that wasn't always the meaning of the expression. When the expression first turned up in Scotland about a hundred years ago, it was lacking the lighthearted touch it has today. In those days 'pull one's leg' meant to make of fool of him, often by outright cheating. The best theory of the origin of the phrase is that by tripping a person -- pulling his leg -- you can throw him into a state of confusion and make him look very foolish indeed." From "Morris Dictionary of Word and Phrase Origins" by William and Mary Morris (HarperCollinsPublishers)." - phrases.org.UK
Fortunately, when you have pulled pork instead of a pulled leg, something very different happens. You look very wise indeed, and people are way too busy eating to even think about laughing at you. Lightheartedly or not.