Things in the air tend to make people disappear too.
I work in a company fleet shop setting, so "customers" per se are not a problem, but when the wrong people otherwise want to congregate in my work area, for the wrong reasons......this is what I have done (been years since)
In the old shop I worked in (we have since moved to a different location), members of the "smoker's club" wanted to use my work area to congregate and smoke their cigarettes in inclement weather, including a supervisor who smoked. (shop rules and state law prohibit smoking tobacco inside buildings), and I am a non-smoker, so I was peeved at their actions.
Whenever they would attempt to "hide" in the back of my work area to light up, I would light up a forklift engine and squirt motor oil on the exhaust manifold and exhaust pipe.............then I would go to the restroom.
Exhaust components sure do heat up quickly when you push the tilt lever into bypass mode at governed RPM.