I'm 18 and eat a frozen pepperoni and sausage Red Baron pizza every night for dinner. Is this bad?

Yes, you should more healthy and more a variety

Not if you don't want to live past 40.

That must be boring as Hell. You really should cook healthier, more nutritious meals, using fresh ingredients.

Yes, you need balanced food groups.
You're getting grains for the carbs.
Protein is in the pepperoni & sausage.
Dairy is contained in the cheese.
Add some vegetables like peppers etc.

It's bad.

ever hear of arteriosclerosis?