Here in the USA we have Shooter-Guys who wear sexy underwear and carry a tray of jello shooters and sell them for $1 to customers. Most guys only buy the shooter because they want to get close to the sexy guy. They give the guy the $1, tell him what shooter they want, the guy puts it in the holder near his crotch and the guy has to bend down and suck the jello shooter out of the cup but to everyone it looks like the guy is giving head to the shooter guy....
Knowing Thailand, I could imagine guys climbing up on chairs and feeding guys jello shots from the crotch holder much the same way the guys in the puppy costume use to hump the faces of happy guys during the show at Throbb.
To encourage the sale, let the shooter guy or guys earn 10 baht for every shot sold. :alc: