Because you have to change them.
A Brazilian.
Soak it in gasoline, hold a match up to it, and "woof!"
They're always looking for Grant money.
Wasn't there a joke before posted about asking what a girl would do for $20 or something A dirty joke I'm trying to find it but I can't....
Pamperspired.
They both need to be changed after a while for the same reason
Littering.