Weak Vegans?

Today a kid at school offered me a huge chocolate chip cookie today and I said "no thank you" and then I told him I was a vegan. And he said "why?" so I told him everything I know and he told me that I would always be weak because all vegans ever eat is lettuce and tofu and that I need to eat meat to bulk up. I said I can gain lots of muscle by eating vegan foods only. So I looked into it and I saw these freaken amazing vegan and vegetarian bodybuilders. They have so much muscle it's just crazy.