You will need only red food coloring, oven, toothbrush, bowl, knife, and that's all.
Step 1: Making the Powder
Get the red food coloring and put it in a oven safe bowl and put it in the oven for about 25 minutes. Take it out and scrape out the food coloring and put it in a bag to store.
Step 2: The Prank
Take the powder and put a small amount on the bristles of the toothbrush. When the person goes to brush there teeth, lots of red food coloring will come out and scare the unsuspected victims. Thank you and please vote for me In the pranks contest.