You can have flash cards. Put a number on them and give at least 10 people a number and to do that close your eyes and pick 10 people. Now shuffle your flash cards up. Oh, yeah, and you don't have you give them a number in person, like find a picture of smokers and non-smokers and tape a number on your computer on the spot of their shirt. So shuffle the cards and pick 5 of the numbers now you're done!