Or whatever you want to call it. I have a specific amount I carry with me at all times that is for “emergencies” only. A great sale is NOT an emergency, grabbing a burger is NOT an emergency. I am talking you are away from home and boom you have a flat, or something like that which takes just a little cash to get it fixed and out comes the rat hole money for it. More than once has that money saved our bacon when we are traveling. Because those emergencies often happen when the banks are closed and I can’t move funds immediately.
Or like when we were traveling to Las Vegas two years ago through AZ and none of my bank cards would allow me to run debits in AZ. That rat hole money put fuel in our truck to get us out of AZ.