One size up from a ten year old boy. Or it can be one size down from a twelve year old.
For a 12 year old boy, the best underwear is the boy shorts.
An eleven year old boy should have 2,300 mg a day
Simply asking would be ideal
A 10 year old boy should wear underwear to school and everywhere else. Underwear serves as protection.
plastic or absorbent underwear
Although it depends on personal preference it would be best for a 12 year old boy to wear boy shorts when wearing girls underwear.
well if your good then you've skated before so get what ev is comfortable
The girl underwear style boy shorts would be the most comfortable (above thong, hipster, ect) for a 12 year old boy.
A hipster is the best wear for a 12 year old girl.
You should make a list of the pros and cons, plus why you want to wear girls underwear. As a 12 year old boy, you will need to make your mom understand why you do not want to wear boys underwear.