I would not have tipped that guy.
I waitressed in college and I normally tip as well as I can afford. I was barely adequate as a server.
I have been known to leave notes for servers entitled "TIPS for [servier's name]" with suggestions for how that server could improve his or her service. Once I wrote a numbered list for someone who berated my son for ordering a milkshake. He had gotten braces tightened that day, was in pain, and we had promised him a milkshake. The server didn't want to make it. The service was poor in other respects but mostly I remember her upsetting my son. I explained to her that embarrassing a teen dining with his parents just is not done, that we were regulars in that establishment, and that she would not be serving us again. I may have left 50 cents on top of the paper I wrote on.
Actually I never saw her again so I don't think she lasted long there.
I waitressed in college and I normally tip as well as I can afford. I was barely adequate as a server.

I have been known to leave notes for servers entitled "TIPS for [servier's name]" with suggestions for how that server could improve his or her service. Once I wrote a numbered list for someone who berated my son for ordering a milkshake. He had gotten braces tightened that day, was in pain, and we had promised him a milkshake. The server didn't want to make it. The service was poor in other respects but mostly I remember her upsetting my son. I explained to her that embarrassing a teen dining with his parents just is not done, that we were regulars in that establishment, and that she would not be serving us again. I may have left 50 cents on top of the paper I wrote on.
Actually I never saw her again so I don't think she lasted long there.