That is a great story!
I experienced a memorable moment in a restaurant a few years back, also watching a group of deaf teenagers. There were probably about ten of them with a couple of adults with them.
They looked and acted like most rambunctious teenagers at a place like that do...but in this case, they were signing madly to each other.
There were two of them, face to face, signing furiously at each other. The longer they were face to face, the faster the signing got, and the higher their hands got, until their hands were directly in front of their faces, so they couldn’t probably have even seen each other’s faces.
Suddenly, one of the adults appeared right in front of their hands (facing me) and calmly placed his his hands on top of theirs, his left hand on one kid’s hands, his right on the other pair.
They stopped signing, and the adult slowly pushed their hands down to the bottoms of their thorax.
For a split second it didn’t hit me. Then it did all at once., and I nearly fell on the floor when it did:
“Keep your voices down.”
LOL! That’s exactly the experience I felt with those folks. They were having so much fun, that’s when I told them they were out of control, in a fun sort of way. They so appreciated to be accepted as normal in a normal environment, it’s in my top 3 waitress experiences. They wrote the president of the company to let him know how much fun then had and how their server made their experience memorable.