You know what it is for, but the design leaves things to the imagination.
I just imagine someone using it as a perverted "Operation" game with a buzzer if you insert the black dildo into a wrong one.
Or a group using it at the same time, trying to reach the end at the same time and, with their combined ejaculations form a small geyser from the middle hole.
Or even that scene in Flash Gordon with the wood beast, with two contestants inserting their dicks into a random hole, but they are told one hole has a mouse trap.