Adjective: describes a type of person who appears untrustworthy or sketchy, and will quickly encroach physically on your personal space whenever you are not looking at them directly.
Note: Usually best dealt with by putting as much space as possible between you and this person(s) immediately.
Sometimes you will need to use a long, very hard and intimidating stare to shame them into backing off. This is what you can do if you are not able to leave the vicinity immediately, for example you are in line at the grocery store.
"Whoah, did you see that skritchity dude behind me in line? I thought he was going to grab my money right out of my hand right there in the store!"