Novelty motorcycle helmets are just what they say, novelty items only and she not be worn for protection on the roads. You can wear them to look cool, but expect little to no protection. Novelty motorcycle helmets do not carry a DOT rating...or any street legal rating for that matter.
The most these helmets will protect you from is road debris, bird poop (maybe), and a smack upside your head from your old lady for looking at that cute chick that just walked by. And visa versa ladies. These helmets were designed to be an extremely low profile helmet that fits very close to your head...eliminating the ever-so-dreaded mushroom look. However, you will not fool Johnny Law with these lids. They're wiser to these helmets.
ATTENTION!!! Novelty Motorcycle helmets are not DOT rated and highly advised against for safety equipment on the road. They are not proper protective equipment and will not protect you in the event of an accident.