There we wandered around at first without getting undressed. Or rather we went joking around, mixing with various groups of bathers at their games. Suddenly we caught sight of an old, bald man in a long red undershirt, playing ball with a bunch of curly-headed slave boys. It wasn't so much the boys who took our eyes......as the old man himself. There he stood, rigged out in undershirt and sandals, nothing else, bouncing a big green ball the color of a leek. When he dropped one ball, moreover, he never bothered to stoop for it, but simply took another from a slave who stood beside him with a huge sack tossing out fresh balls to the players. This was striking enough, but the real refinement was two eunuchs standing on either side of the circle, one clutching a chamber pot of solid silver, the other ticking off the balls. He was not however, scoring the player's points, but merely keeping count of any balls that happened to drop on the ground. While we were gawking at these elegant gymnastics, Menelaus came rushing up. "That's him!" he whispered, "that's the fellow who's giving the meal. What you're seeing now is just the prelude to the show." These words were hardly out when Trimalchio gave a loud snap with his fingers. The eunuch came waddling up with the chamber pot, Trimalchio emptied his bladder and went merrily on with his game. When he was done, he shouted for water, daintily dipped the tips of his fingers and wiped his hands in the long hair of a slave.
One slightly (to the modern world) inappropriate phrase has been omitted without affecting the content. The entire tone of this passage is satirical. The statement that they counted the balls that dropped on the ground instead of the player's points may be a humorous comment on how bad a player Trimalchio was, but a careful reading of the original Latin suggests that this was an "innovation" in the scoring of the game. It was apparently common practice, up till that time, for a player to score a point when he caught a ball. Scoring on a drop, however, does not in any way change the nature of the game and would seem to provide for more motivation on the part of the thrower. Scoring this way also bears more similarity to that of handball.
The passage implies that the player with the ball, in this case Trimalchio, bounced it, and it must be surmised that he bounced the ball to the other players. Balsdon, who used this same translation by Arrowsmith, seems to ignore this fact. Not all translations use the term "bouncing", but Arrowsmith's translations are exemplary.
Following is the original Latin, which the reader may note does not refer to the game as trigon or the players as trigonalis. Nor does it refer to the ball as a trigon, and it twice refers to the circle they play around.