Oh I've remembered a couple more.....................................
This is more a practical joke but I did this to a friend that I used to board horses with. She used this really expensive liquid supplement. I poured it into another container and LABELED it. Then............................. I mixed school glue and brown paint (use the color or the supplement) really well, pour it into the washed out supplement container, then tip it over onto a piece of plastic wrap and let it dry for 48 hours. It sent her directly into ORBIT. I lost it when she tried to scrape it back into the container. I was glad all the pitch forks in the barn were made out of plastic.
Here's a nice one. Knox Gellatin, water, scent, water and silk flowers, sea shells, nick nacks, food coloring. Make the gellatin drop in the food coloring, scent, and pour into votive candle holder or any other small decorative dish add the nick nack and let harden. Its an air freshener that lasts a long time.