Originally Posted by
himespau
I've always head the U police around here use a long 2x4 as a lever and just pop the u off. Don't know if it actually works or not, but if you've got an old 2x4 lying around, it might be worth a try...
That's why they say to fill up the area inside the U with as much stuff as possible (frame, seatstay, rim, parking rack) ... so they can't get the pry bar or jack in there.
Still, I've seen some U-locks break with remarkably little effort. I know a guy who had one on his motorcycle - just through the wheel; he forgot it was on there, put it in gear and the lock just snapped - no damage to the wheel.