It is illegal to wear them in high school for safety reasons.
Yes you can wear a skull cap under a ski helmet.
some where "skull caps" which is like a compression type of material but in high school its a rule that you can't wear anything under your helmet
Nope
Possibly because she's famous?
Wearing a hood under a helmet while riding a bike can compromise safety. The extra fabric may interfere with the helmet's fit and stability, reducing its effectiveness in protecting your head during a fall. Additionally, a hood can obstruct peripheral vision and increase the risk of accidents. It's best to use a helmet that fits properly without any additional layers underneath.
Wearing a cycling cap under a helmet can provide benefits such as moisture-wicking to keep sweat out of your eyes, sun protection for your head and eyes, and added warmth in cooler weather. Additionally, the brim of the cap can help shield your eyes from sun glare and rain.
It keeps the sweat out of their eyes. Football players sweat a lot under those helmets and when they take them off, it will roll into their eyes. Some guys wear the skull caps under their helmets for the same reason, and so that their helmet doesn't pull their hair out when they take it off.
Skull cap, like from under armour
Helmets have always had earholes in football.
A Du Rag under the helmet underarmour shirt and compression shorts with some hood tube socks
You can use a toque under a helmet but if you are looking for warm you can buy a cover that goes over the helmet. I have one that works quite well Check out this link. http://www.horse.com/Winter-Cozy-Helmet-Cover-RBC35.html
In CA you can. Other states I don't know. In most states you can only get a ticket if you are under the age of 13 and without a bike helmet, but again, this varies between states.