It's not illegal to write upon, only to damage or destroy.

You still have a typewriter?

Yep. Defiling US currency is illegal. I don't know how you can go to an amusement park and put in a penny to smash it into a souvenir of the place. I've heard they have to pay a huge tax , or get some sort of permit.

“..bills have to be defaced or mutilated in such a way as to make them unusable as currency before it is a crime. It is not a crime to cross out "In God We Trust" and write "No We Don't".” - Yes, unless you have attempted to alter the serial number or denomination of the currency it remains ‘a legal form of protest.’

I believe you're mistaken.

@Varn Exactly Thank you

Ones, fives and twenties are so common it is difficult t impossible to trace unless you do it in bulk; however, uncommon bills, such as the two, get attention. A clerk might remember the face of someone giving them a defaced two dollar bill.