Flat fix...

I changed a Phillips screw in my tire for a new one once just to mess with a friend.
Told him it was easiest if you caught it before it wore the head off, because you could use a screwdriver and unscrew it and screw a new one in instead of pulling it and making a bigger hole so it needed a bigger screw every time.

I can keep a pretty straight face when BS'n.:D
Would only have been flat on the bottom anyway