"I did this one last year. I work at a restaurant. We have these spray bottles with a light pink solution we use to clean tables and such. I went and grabbed a brand new one and filled it with watered down pink lemonade.
I would be cleaning near my co workers , while chatting with them and nonchalantly unscrew the top spray/ trigger piece and just started downing it like I was dying of thirst.
The look of horror on some of their faces was priceless."
watch the guy that has the job of setting them forward wonder why the clock are still wrong after he went around the office