Years ago when I worked in a bar, myself and the barman ended up at my house the worse for wear (lock in). I had lost the keys so he had to climb over the back wall to open the back door. In doing so he grazed the whole inside of his arm. Me being smart decided to get a basin of water, some cotton wool and some germolene to fix his arm etc. No problem. Got up the next morning, a little groggy, and saw two cups of coffee and thought 'oh thats right, xxxx came back last night', then I saw the basin of water etc and remembered how he had hurt his arm. While putting everything away I discovered that it wasnt germolene I had put on his arm, oh no, it was a vaginal cream for thrush!
I never told him. Turns out his arm was fine (thank God).