Joel Bowl means in slang: Unopened sacks or bowls of Marijuana can be purchased for $5. The smallest one-hit hit and most five-hit hits are the typical sizes. A Joel Bowl is only good if there are five friends or less. If a friend is a regular offender in such cases, they earn the nickname. You will get less for what you put in. Beware of this friend. (in Slang Dictionary, added by Bridget Bartlett)