Would eating popcorn aggravate a gallbladder?

Possibly: If it has a lot of butter on it which is fat it could aggravate a gall bladder. Normally fatty or greasy foods aggravate a diseased gall bladder.

Usually not: Traditionally, fatty or spicy foods can flare up an inflamed gallbladder. Plain popcorn isn't spicy or fatty -- unless you add butter, which is pure fat. If you're getting honest-to-goodness gallbladder attacks ("biliary colic"), you should have your gallbladder removed. That said, many people with irritable bowel syndrome have innocent gallstones that won't hurt them.

Billiary colic: Pain with gb "attacks" is usually related to fat containing foods like butter , but also can based on the severity of the disease can eventually be related to all foods. Meet with your GI or surgeon to discuss.