I stumbled across this news article: "Shop posts ingenious 'August peanut sale' poster to circumvent bottled water ban"
The article describes a music festival that was not allowed to sell bottled water to patrons, so they sold peanuts for $1.50 each and provided a "free" bottle of water with the purchase. The overall result is that the customer has paid $1.50 for a bottle of water and a peanut, but because the money was ostensibly exchanged for the peanut, nothing illegal has taken place.
In fact, the placeholder purchase is not required, because each person could claim that they gave away the money or the item of their own free will, independent of expectation from the other.
I'd like to know if this loophole, regardless of the goods that are forbidden to be sold, has ever been challenged in a court of law and what the outcome was. I don't care too much about jurisdiction but I'd prefer answers from the United States or countries with legal systems descended from English Common Law (Australia, Canada, United Kingdom).