You mean...a u-lock type got jammed w/ one end stuck where bars and stem meet, and the other end immobilized against the top tube?

I had exactly one close call with that annoying (loud clanging, unbalanced bars) habit and swore it off completely. It sucks to be pedallin' along and suddenly have your steering "locked." I was headed to a plate glass storefront at the time, and barely missed endo'ing.