My sister moved house and noticed a weird smell from the kitchen sink. Plumber found a mini fatberg down the drain. The old bloke they bought the house from had been tipping everything down the plughole. For years.

(the emoji itself is nauseating)

How does this happen? Is it more for things like bacon grease rather than cooking oil? Because cooking oils are usually (not always, coconut oil for example) liquid to lower temperatures than water.