The kids were awful to Vern. Why was he friends with those jerks?

They didn't beat him up, so it was a win for him

It's part of being a boy. it's good for you. Grow a thicker skin and it helps you lose weight as a fat kid if your bros poke fun at you. I'd never call a stranger fat but when you've been friends with someone for so long you kind of stop censoring yourself. That's a good friendship to have when you can do that and still be friends

Who else was he gonna hang out with?

I think of it like Will Smith’s treatment of Carlton in Fresh Prince. There’s a lot of teasing, but both sides understand that it’s done out of endearment. I’ve had friendships where there was constant teasing like that.

I feel awful admitting this but my group of friends around this age we had a friend who was one the chubby side and she was very much like Vern. We all saw this movie in theaters and it was so funny to see how out of the 4 of us we were a lot like one of these characters. She was Vern and I was Gordon. Yes, we did treat her a lot like Vern. She would fall asleep first at slumber parties and we'd put food in her mouth, she would actually eat it most of the time. We'd laugh when she would wake up and say "Guys what are you doing to me?" Now, as an adult, I see we could have caused her to choke and we were mean to her, but that is just how it was back then. These days it would be bullying and I don't think her parents would have allowed us to stay friends with her. But, just like Vern she never ever got mad at us. She didn't really care and if you ever needed a shoulder to cry on or someone to listen to you she was there.