Inspired by this thread:

Say for example, there are two players in a trade world. Someone wants to sell a double growsaber for 12 world locks and someone else would also like to buy a double growsaber for 12 world locks. Imagine the seller's name is seller and the buyers name is buyer. If the buyer typed "/billboard seller", if both parties had the respective items required for the trade (12 world locks and a double growsaber), the final page of a trade would appear, requiring both people to accept the offer. Basically, based off of the billboard and if both people have the items required, the trade will initiate and complete itself, however it will still require both players to accept, in case they change their mind or it isn't convenient. This would also save a lot of hassle when it comes to royal locked worlds where people can't talk.