toothpaste rule

This rule describes the phenomenon where when you get new toothpaste it'll only taste weird for a day. This rule can be applied to any event that becomes common place after about a day.

"Dude, my new toothpaste tastes horrible!"
"Don't worry about it, remember the toothpaste rule."

This was a term coined by Gavin Free from Roosterteeth Podcast #370.