The Great Evil Villain Planning Session

As a truly evil villain you need to come up with a new way to get rid of people who get in your way. Luckily there is a new building going in right across the street from you so disposal of the bodies is going to be pretty easy while they are digging out the foundations and then pouring concrete. It's the in between that you need to work on. Poison seems ideal, less messy than shooting and stabbing. But, how do you get them to take the poison, not knowing it will be their last day.