Everyone's got to make a buck however they can when they have bills.
For several years of my college life I worked as a janitor for the school I attended, work most of the night, take classes during the day, who needs sleep. This is one of those jobs were people think nothing of you and you become invisible. But invisible has its advantages and you'd be amazed what you see when people forget your there.
For a stretch of several months I covered the environmental service needs of the campus business college at night on my own. The day to day work didn't really need more than one person and when there were big events extra hands would always be assigned.
One of my tasks was to close the facility at midnight and lock the building down. Usually I gave the building a once over some fifteen minutes before midnight. Locking the doors first then making my rounds this way no one else was getting in while I was sending people out. This way I could give anyone on hand fair warning and get a idea of who was around or things I would need to deal with.
On this particular night some forty minutes or so before closing a young couple came in by the looks of them campus juniors or seniors. The young man was a fairly nondescript blond, corn pole thin and tall. His companion was a cute well proportioned young lady of Asian background. They happened to come in while I was in the lobby checking on the main offices. As they passed me by heading for the stair I informed them off the impending facility closure that would be occurring within the hour. Until I did my lock down rounds that was the last time I gave them any thought.