Tipping for haircuts?

[Semper Fi]

Had a late lunch party of about 17 people, a party for my daughter. I didn't pay for everyone, was about 6 checks. But we had the cool inside the kitchen table at a PF Chang. When it was all over, I know the kid serving us worked his a$$ off, best service I've seen for such a large table of people. Anyway, I put 18% on the CC for the bill but also handed him $20 cash for going that extra mile the entire time. I know he'd have to share the one on the tab with the bartender and the bus staff, but that $20 he got to keep without saying anything.

[Dandelium]

I leave a tip only if I am satisfied with the service in the restaurant. I'm not too picky, I did not leave a tip just two times. Once I waited for the waiter for more than 20 minutes, while apart from us only a few tables were occupied. The second case was when my wife and a waitress had a row in a cafe because our son (he was only 2 years old) had been eating carelessly (I think my wife or I would have cleaned after him table and seat, as we did before, if the waitress didn't start a quarrel as soon as he poured out the soup). Both times it was a roadside cafe. I sometimes leave a tip where I like to communicate with people. For example, a courier who often delivers me goods from one online store. I'm glad to chat with him for a couple of minutes and usually leave a tip. I leave a tip or pay extra for services that I additionally provided.