As a Canadian, I believe it's my duty to apologize to all those from the state of Hawai'i who have to explain that it's not a staple food.
"Hawaiian pizza" is a Canadian creation. A Greek immigrant to Ontario wanted to match Chinese sweet and sour flavor that was really in at the time, and selling really well at his restaurant. In 1962, he took a can of pineapples, strained them, and put them on as a topping along with ham to see if it would sell. He named it "the Hawaiian".
It did, the rest is history. Gross history (I'm in the no-pineapple on pizza boat).
If you don't like salty things such as olives or sardines, don't try squid ink pizza. Really popular in the Asias; I just bought a pack of squid ink so I can give it a try. Odd toppings I've never tried: fried eggs (France/UK), coconut/shrimp (Costa Rica), and dessert pizza. Can't really figure out if I'd use a cookie for the "dough", or some sort of pastry.
My worst topping is donair/donair sauce. It's unique to Halifax: the sauce is made from condensed milk, sugar, garlic, and vinegar. The meat is pretty much identical to gyro meat. You can use either pizza sauce and have the gross donair sauce to dip, or use the donair sauce as the base. Here's a photo:
Example of Donair pizza. Any time I've seen it, it seriously looks like someone has jerked off on your pizza.