booger

1. A bogeyman.
2. Slang. Dried nasal mucus.
3. Slang. An item that is unnamed or unnameable: “It's . . . like a pop-top . . . one of those sharp little boogers you pull off the beer cans” (Hunter S. Thompson).
4. Slang.
   1. A worthless, despicable person.
   2. A person; a fellow.

[Origin unknown.]

The noun has 2 meanings:

Meaning #1: an imaginary monster used to frighten children
  Synonyms: bogeyman, bugbear, bugaboo, boogeyman

Meaning #2: dried nasal mucus