Users are able to put just about anything from special characters to single names or even mistakenly think the field is meant for the password, while the second field is the confirmation of it, like for other services.

Suggestion

Add a field validator that won't allow special characters into the field such as @!#$* and require that at least two words are put into the field.

Exceptions

Add exceptions to singers like Madonna, Ke$ha, Bono, Eminem, etc.