Rude.

So we have this one family that comes in... oh, three or four times a week. They are strange.
Son, mom and dad, and mom's dad - who is clearly too old to be in public.
They order at least forty dollars worth of food between them. Sodas, dinners, soups, something to take home, etc. Then, they let Grandpa tip, and he always leaves a five. I appreciate this because I'm sure in his mind, this is a great tip. And hey, five dollars is five dollars.

HOWEVER, mom and dad know that he leaves five dollars. And they know what the bill is, because she pays it. And yesterday, she paid with a hundred dollar bill.

You couldn't have slapped three extra bucks on there and given me twenty percent for being nice to your cranky husband?