Unexpected mitzvot

I'm looking for input here, a name to call the act of bestowing unexpected charity or good will on another individual. Some names that have been suggested: Surprise Mitzvah; Unexpected Gift; Drive By Charity; Mitzvah of the Moment. I'm looking for something short and catchy. Here's what happened that made me consider this subject. I was driving back from dropping off the rest of my son's "stuff" at college. I was exhausted to the point where I was truly afraid I might fall asleep at the wheel and to make matters worse the traffic was heavy with the usual number of trucks, everyone was driving at least 70+, and no sooner would I enter the left lane to pass when I would notice a huge SUV loom in my rear view mirror mere inches from my tail apparently trying to run me off of the road. It was stressful driving to say the least and exhaustion didn't help. I decided to stop at the Pink Cadillac Diner for a dose of caffeine and possibly some food, remembering that I had eaten only a bagel and it was now almost 5pm.

I sat down at a booth in the "Elvis Room" and looked at the specials and the regular menu. I was groggy from driving and from exhaustion and my eyes just flitted from one part of the menu to another as if with no ability to focus on any one item. The waitress was standing very patiently waiting for me to make up my mind; she looked tired too but a different kind of tired than that which I was feeling, more of a resigned to life kind of tired. She was understanding when I told her that I had been driving and needed a few minutes to collect myself and decide what I wanted. She came back again, I ordered a coke. When she returned she asked if I was ready or did I need some more time. She seemed kind and sympathetic and willing to be patient with my indecisiveness. In the end, I ordered only soup and a fresh from the oven homemade apple crisp with vanilla ice cream which was out of this world delicious. But, the check didn't amount to much and the waitress had been very understanding. And I realized that she couldn't make much money from this job and my dollar bills would mean more to her than to me. So, on the spur of the moment I decided to give her a larger than average tip. Not huge, but 40% instead of 20. I just left the bills on the table. No note, no explanation. I did hope she noticed before stuffing them into her pocket but it was ok if she did not. (Jewish law says that anonymous giving is the highest form of charity, and when both the donor and recipient are unknown to each other is even better.)

I suggest that for our own souls and for those of others that we practice random acts of charity regularly. What shall we call these acts? Send me your suggestions.