Pizza has always been for the majority of Americans and certain first-world countries a food that people can agree on.
However, there is one thing that people can't agree on. When given the choice of two toppings, it can lead to a brawl, verbal or physical.
Since there are numerous combinations, it sounds like I have an open-ended poll to run through.

My two toppings are bacon and red onions.

What are your choice 2 toppings? I would like to see how this plays out.

For me it's either a particular meat sauce covered in cheese with bacon bits on top, or (tomato sauce & cheese at the bottom with) pepperoni and bacon on top (but if it also has garlic-meatballs and/or beef, I'm really happy).

I'm not too particular when it comes to pizza, but if I make it myself or order at a restaurant, this tends to be what I default to. If I can have all my favorites on one pizza, then I'll take that.

(I don't count tomato and cheese as toppings, as those are a must - otherwise it's not pizza but bread with topping).

I've read some Europeans use "odd" toppings like corn. The Japanese are fond of squid ink pizza.

I lived in another part of the USA (in metro NY now) and people would use pineapple on pizza. I think my pisanos would kick your *** here in NY if you put that on your pizza. (Just kidding).

I like to make my own (pizza doesn't agree with me anymore) and use green pepper and black olives. I also like pepperoni but I am giving up meat slowly and especially not eating cured meats right now.

Some restaurants may have taco pizza, which could include corn. I guess veggie pizza also might have corn. It's not the most unusual topping I've heard of, but it's not one of my favorites. Squid ink? Nopetynope and no thanks from me. Pineapple is more of "either you like it or you don't" - I like pineapple, don't mind warm pineapple in sweet&sour, but it's far from a favorite on pizza.

While I like pizza I try to stay away from it, but mostly because of the dough (my stomach more often than not disagrees with flour/grain). The toppings aren't bad, though.

Weirder toppings in my opinion are shrimp, fish, rocket/rucola salad, peanuts or avocado (which are all examples I've seen in restaurants, and found a bit too weird to try. I have tried fish once, and never again...). Not a big fan of olives or tomatoes either (cut then baked, or cherry tomatoes - tomato sauce is perfectly fine as long as the sharp tomato-y taste from raw tomatoes is gone).

I think Gordon Ramsay would also kick your butt of you put pineapple on pizza.
For me I love putting;
Prosciutto, Avocado, Salmon, Spanish onions, spring onions (I think Americans call them scallions)
Maple bacon (I sugar the bacon up and then put it in the oven)
Hot pork sausage

Jalapenos, Spinach. Because I'm a south westerner.

Two is difficult, because everywhere with a "create your own topping" option round here does 4 toppings - I usually pick: Jalapenos, tandoori chicken (or any spicy meat available), green & red peppers and extra cheese. I guess if I was to pick two - Tandoori chicken/any spicy meat and peppers. I do really like ricotta & spinich pizza though too!

I like to mix things up. Today, I want pepperoni and sausage. Tomorrow, there will be mushrooms, next week, anchovies...

2 isn't enough for me. I like everything on pizza.

Depends on the pizza. If its home made then it can have all the things, but if I'm ordering from the place near me: pollo hawaii- so its spicy chicken and pineapple

Addendum: I will leave the debate on pineapple to the user, like controversial rights to the states.

Pineapple on pizza with chicken or ham is totally acceptable in this part of Europe. What's not ok is what they have way up North in the Nordic countries: banana and pineapple, and other (horrifying) combinations.

I think you're missing out- like spicy chicken with the sweet and sour from the pineapple with some garlic sauce on top? Best thing ever with a nice cold class of coke. But not all pizza places are created equal. I only eat it if its from the place near my house.

Mushroom and olives.

Cheese and more cheese

Blue cheese crumbles and hot sauce. Weird combo I know, but It's what I get at my favorite pizza place. (lol now I crave pizza. I wish I could go there now that I think about it but the stupid virus)

Golden corn and Mushrooms

Pepperoni or nothing. I'm basic, huh.

The souls of the innocent and pineapple.

Mushrooms and pepperoni