Everything from peanut butter to hair gel to that emergency tube of toothpaste. Even your favorite jar of jam is a liquid! The rule also applies to mascara, lip gloss, and those delightful stick deodorants that look solid but actually aren’t (check the label).
Pro tip: Snow globes? Yep, they’re liquids too. So unless you want to check your souvenir, keep it small or ship it home. Trust me, your checked bag doesn’t judge.