...and even if your name/surname was forced, you still have the choice of entering a real or fake name so either way you still have a choice.
You could have something like:
First Name: <text>
Last Name: <text>
Anonymous: <radio>
If anonymous was selected, first name and last name could be just filled with "Anonymous"
You could have something like:
First Name: <text>
Last Name: <text>
Anonymous: <radio>
If anonymous was selected, first name and last name could be just filled with "Anonymous"