What is top lip?

Something that does not exist.

Jimin’s top lip is covered with concealer to appear nonexistent.

Army: Did you know Jungkook has a pet fish?
Other Army: That fish is as real as Jimin’s top lip.

Top lip - what is it?

When you spent money on something you didn't intend to buy, your top lip extends beyond your bottom lip.

After work my girl asked to stop for a drink, on her, when the bill comes she says she forgot my wallet so I top lipped and paid.