system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it ok to smash pennies, but not deface currency?

Those penny smashing machines that used to be popular near famous landmarks always confused me. Why is it ok to crush pennies there but not, say, burn a dollar bill.
gpt
Burning a dollar bill is legal. It's not legal to deface currency with the intent of counterfeiting it or defrauding someone with it. Smashing a penny into a commemorative souvenir isn't either of those, so it's valid. Illegal would be tearing a $20 bill in half and trying to spend each half in two different stores as two different $20 bills.