I have always been strict with my extroverted feeler son about safety: mostly this means bike helmets. I tell him that I do not care if his friends aren't wearing them. He'd better, because we live in a small town. If I hear from some other creditable adult that he was on a bike or skateboard without his helmet, he'll lose privileges until I regain my temper. It could be months.
One day there was a knock at the door.
I opened it and there were 6 teenage boys.
"Is EF home?" said one of the boys.
"I'm not telling you." I said.
"What?" they said.
"You have skateboards and you don't have helmets. I don't want him to ride with you." I said.
Slightly dumbfounded silence. "Um, will you tell him we came by?"
"No. Go away and come back with helmets." I said.
They left, shaking their heads.
About 30 minutes later, there was a knock.
The boys were back, this time with skateboards and helmets.
This time I called the Extroverted Feeler and he went with them. I'm not sure any of them wore the helmets, except for the Extroverted Feeler. I don't think his friends give him too much grief, since they think his mother is insane.