Snoopy (adjective)

1. Curiously or excessively inquisitive; nosy.
2. Acting in an excessively curious or inquisitive manner.

Origin:

Refers to the character snoopy from the comic strip peanuts.

Examples:

1. The snoopy neighbor always seemed to know everyone's business.
2. The snoopy reporter asked too many questions.
3. The snoopy employee was always looking through other people's files.
4. The snoopy attitude made it hard to trust the person.
5. The snoopy behavior was not appreciated by the others.