My first employer was Waffle House.
I was 16 on a dead afternoon shift after school one day when a couple came in and ordered some steak and eggs. I gave them their silverware plus some steak knives and wait for the food to cook. The only other people in the building are the meth-seasoned cook and this little old man and his little 6 year old daughter, so I'm back on my homework while I wait.
Another group comes in, three guys. I'm getting their menus ready so I can seat them and they were already gone. Whatever.
Five minutes later one of the guys comes back, walks swiftly and directly to the couple's table, grabs a steak knife, and tries to STAB THE GUY because apparently the woman was his girlfriend and the guy was now persona non grata for Stabby Man.
Before I even process what's going on, Little Old Man has teleported across the dining room and grappled this guy into a secure hold. Meanwhile he's speaking to me in a sweet gentle grandfatherly voice, telling me to get the phone, call 911, etc.
Turns out the little old man was a retired Texas Ranger and if he wasn't there that day, that probably would have been a really messy, traumatic day for everyone.
Again: this was a Wednesday afternoon in full daylight, not 4 am Waffle House Chaos Afterhours