Went to deliver to a house and this shirtless kid (probably 16 or so) answers and I can see a lady (presumably his mom) sitting in a table in the back. He hands me the money and tells me to "keep the change"

It was $20 on a $19.86 bill As always, I have my internal sigh and tell him to have a good night when I hear from the back of the house

Mom: "Wait! Did you tip him?!"

Kid: "Ugh, I told him to keep the change."

Mom: "What?! If I were him I would tell you to take your 14 cents and shove it up your ass! How DARE you not tip the pizza guy! (to me) Don't go anywhere.

And she comes back and hands me a nice $5 tip and apologies for her son. I just gave her the most sincere smile I had and told her how much I appreciated it. Not an unheard of story, but always nice to see people out there who care about us pizza guys.