An over the
top pizza where the topping threatens to fall off in an
avalanche, usually created at (drunken) make-your-own pizza parties where the goal is to produce the gnarliest, most
spectacular-looking pizza.
Dude, check out this pizza I made: it has cheese,
ham, mushrooms, chourico, tomato, garlic, pepperoni, salami, habanero peppers, artichoke, chicken (whole), eisbein, peppadews,
pineapple, more habanero peppers, and avocado. Oh yeah, and a duck.
Now that's what I
call a pizzalanche.