Uh... What? People don't 'have' to wear underwear, it should be whatever they're comfortable with. It's certainly not OP's fault because their cousin decided to be a dick and expose them, which was their intention, to expose and embarrass OP. SMFH.

I don't know. I think people SHOULD wear underwear because HYGIENE.

Yes because wearing underwear with your private parts against the cloth is so much different than wearing pants with your private parts against the cloth... Either way they're touching the cloth.

#6 Except there is usually a difference in fiber the underwear and pants are made of. And if people don't care to wear their underwear I doubt they care enough about their hygiene to change the pants more frequently, as they should if they go commando.