Guess how many Bertie Botts Beans are in the jar.
Clear container
jelly beans (can use the real Bertie Botts Beans)
This is the single most common (and easiest to organize) of games throughout the fandom.
Fill a clear glass container full of jelly beans. Be sure to count and write down the actual number of beans before the contest.
Have everyone make their guesses about the number of beans in jar, and submit them. Using a cauldron pot is always fun. The person with the closest guess to the actual number of beans is the winner. A good prize would be...Bertie Botts Every-Flavor Bean.
For a more difficult version, add a few BB beans to regular quantity of beans, and people must guess the number of BB beans ONLY within the jar of beans.