In Arrow episode S01E14 Oliver makes a joke that he was trapped on an island and his only friend was named Wilson. What does this joke mean? People say that it is related to the Tom Hanks movie "Cast Away", but I haven't seen that movie. How is it related?
The answer plays into itself in two ways:
In the film Cast Away, Tom Hanks' character finds a Wilson brand volleyball in the wreckage and, after giving it a face in the bloody palm print he leaves on the ball, he proceeds to treat the ball as his friend during his stay on the island. Given Ollie was a castaway on an island himself, he's simply using this aspect of the movie to make light of his situation.
However, it's not meant to be a complete joke. During the previous episode (13 in this case) we learn he meets and works with Deathstroke on the island, whose full name is Slade Joseph Wilson. For a period of time Slade was pretty much his only friend on the island.
Wilson was Tom Hanks' only friend on the island in Cast Away. It was a volley ball made by Wilson Sporting Goods.
During an early phase on the island, Tom Hanks became depressed, and opened most of the packages from the FedEx plane storage. One contained this ball. Hanks had a bleeding hand, and he smacked the ball with his palm, accidentally creating a pseudo face on the ball. This face and the ball became his island confidante.