Many years ago I was superintendent of an island park in an urban harbor. In the middle of my first summer one of the overnight crew got fired by the foreman and the other quit, so there was no one to do the overnights alone on the island with its great granite fortifications. So for three weeks after work downtown, I'd hop on one of our motor boats and head out to the island to spend the night. The island was closed to the public after 5, when the day crew left, and so I was alone. I'd head up to the cannon ports and smoke a bone before settling in for the night in the administration building.
On my second night as I was walking back to the admin building after smoking a J, I heard the sound of a boat pulling into the pier and soon realized it was the state police harbor patrol. At first I freaked out but I had to talk to them in the tight little office where they were sitting when I got back down. They were stopping in for a routine check and to chit-chat with me to make the evening pass. I explained away my reddish eyes and slightly disheveled appearance by saying that I'd been working all day and then came out here and that I was exhausted. I was scared shitless that they would smell the dope on my breath. But then they left. I was shaking, because if they realized I was stoned, they would have either arrested or reported me and I would have lost my excellent job.
Then the lightbulb went on! I ended up needing to do the overnight on the island for three straight weeks. When I headed out for my smoke or after smoking, I would always have a flask of whiskey in my hip pocket. I usually didn't drink that much, but if I heard the police boat pulling in, I'd take a swig. Suddenly my breath would be masked, and I'd have an excuse for bloodshot eyes and a bit of erraticness. They were all drinkers and they could have cared less if I was drinking during normal working hours, never mind after hours.
Moral of the story? Use booze to cover up your pot habit!