Glower

[Couch Potatoe]

to look intently; to stare angrily or with a scowl.

[Julian]

Have an angry or sullen look on ones face; scowl.

[Kit]

To look or [stare] angrily at mentally [wishing] to punch in the [tant].

[Becky]

Glower is a slang for a [Federal Agent], usually used for one in disguise over the internet.
The slang comes from a racist rant by the coder of [TempleOS] Terry A. Davis.
The CIA nggrs [glow in the dark], you can see them when you are driving. You just gotta run em over with your car.