Zirm told Newsweek that Dory, now 10, "knows a fair amount of American Sign Language, and regular dog signals, like sit and lay down—as well as referee hand signals, apparently." ...

Hand Signals for Driving: What They Are and How to Use Them. If all else fails, an arm out the window can keep you safe if you know the signals. William Irvin Lewis Writer Dec 16, 2023.

One of those are hand signals, which he goes to great lengths to protect. But he also goes to equally great lengths to ensure his teammates know the signals, which can be around 30.