Big Bang Theory Quote
Sheldon: Jacuzzi is a commercial brand, hot tub is the generic term, i.e., all Jacuzzis are hot tubs, but not all hot tubs are Jacuzzis.
Zack: Is that like all thumbs are fingers, but not all fingers are thumbs?
Sheldon: Surprisingly, yes.
Zack: Nice. Now, what exactly are toes?
Quote from S04E17 - The Toast Derivation