Tofu: Tofu has protein. This "bean curd" is made of something that scientists have never figured out.
Beans: Beans have protein. Eat some beans.
Protein Powder: Protein powder has protein. Protein in powder form. No it's not meat powder!!!
Protein Bar: Protein bar has protein. Imagine if you had protein powder. Now imagine if you squished it into a bar form, sold it, and made your fortune. What would you buy? Meat, probably.
People: People have protein. People are made out of protein. Why don't you kill some people and butcher them and roast their flesh and eat it, for protein? I bet that the roasted flesh of people tastes delicious with barbecue sauce. What's that? You object to eating people? You object to being butchered and eaten yourself, just because your flesh is delicious? Well now you know how a cow feels. And a pig and a chicken and a goat. This summer, why don't you stop eating animals, for a change? Let's all be friends, not meat friends. Save some money, and save a nice animal in the process. I think you'll find that you can get big and strong without any meat at all.
When a superior species inevitably wrests control of the ruined earth from our feeble hands, you'll want to have a good track record to point to on this.