People who smoke or snort cocaine and get so paranoid they are constantly peeking out the window.
Tommy is so paranoid from smoking crack he’s been standing there all night being a window peeker.
window peeker: define #2
A person who peeks through out a window looking at shadow things, the neighbors, or other random stuff while trying to remain unnoticed.
I heard a noise outside, so I quickly rushed over to the window to peak out my curtains & a shadow person was window peeking back at me. One of us needs sleep. Damn window peekers.