if this were right I would have an 11 inch cock. Furthermore, it seems like this would overshoot most guys, since the average shoe size is 10.5, and the average cock size is well under 7 and 3/4 inches. but at any rate, as has been proven in many other threads on these boards, there really is no correlation between shoe size and penis size, so it ultimately doesn't matter what the equation is, it's still going to be wrong.
Funny joke though, even though I saw the punchline coming as soon as I saw her picking a guy out from the unemployment line.