Two. One to change it and one to yell "Ta-daa!" when he's done.
pi
Oh, please. Like they've ever changed anything that needed it.
A: The balls are lighter and you don't have to change shoes.
Just one. But it takes a therapist three years to help them through the grief process.
Because when people fall off of 'em, they yell AAAAAAAAAAAAAAAAAALLLLLLPPPP!!!!!!!!
Duck!!!
Phillip