Years ago (70's) when I began pounding the pavement in an 18 wheeler doing long haul I would leave tips even though there was a great possibility of never stopping there again.
Then for a year I was doing an inter-province run daily and ate breakfast at the same stop every morning. Pretty much daily there would be 2 - 4 drivers from the company that would stop there for breakfast also about the same time and then head off in the direction of the runs for the day.
There were 4 waitresses and 3 weren't the greatest....4 days and 4 different waitresses. On the 5th day I got the good one for the second time.
After I was done I flipped over the paper placemat and drew a large circle. Within the circle I placed 3 quarters and six nickels (back then this was just a little over the 20%).....2 eyes, a nose, and 6 nickels for the mouth....with eyebrows over the 2 quarters for the eyes....and left...that was Friday and I was the last driver to leave as I had a short run that day and was in no hurry so I nursed a second cup of coffee....most days it was in and out pretty quickly.
The following Monday when I walked in the waitress spoke and said my coffee was on the table and pointed to it. I ordered the same breakfast as I had all the previous 5 days...and she asked if I ate the same thing every day...and the answer was yes.
Now the thing about this was the restaurant was situated such that the windows looked out over the parking lot as well as the off ramp to get to the restaurant...and I was driving for a company with unique looking tucks and a well known name on the highway here... and each truck just a little different. That being said....
On the Tuesday after the coffee was in place....when I walked in...the waitress said it was on the table and pointed me to it...and there sat my breakfast and coffee all ready and waiting for me...and so it was each morning from then on until I switched runs a year later back to long haul. She would see my truck coming on the off ramp and put in the order....and by the time I got parked, hit the washroom, and then entered the restaurant was enough time for the breakfast to be cooked and sitting waiting for me....all because of a smiley face tip....and yes I did keep tipping but not with the smiley face.
And the other drivers never did figure out why my breakfast was always ready and waiting
Addendum...I was switching runs just after the Christmas holiday....in the course of kibitzing with the waitress the week before Christmas I found out that she had asked Santa for a certain sweater but their finances wouldn't allow for it.....so on the 24th of December (my last day on the run), and after I had finished breakfast and gone out to the truck I came back in and handed her a wrapped present and abruptly turned around and left...on the package a smiley face with the words "Just Because"...and tucked inside a little note saying--"Just a little extra thanks and appreciation for making my days a little easier"....my runs never took me back that way again.