This is a cool picture from a series of coffee art on napkins.
Here’s the caption from this one…
My inner accountant quickly convinced me to buy one of those little espresso machines (for the price of approximately 10 tall lattes). It had a steam nozzle to heat milk, which one should clean very thoroughly after each use. I didn’t have the patience to do so. Within a few uses, an unappetizing, dark brown, organic lump developed around the nozzle. A few days later it had become unremovable, and I reverted to getting my coffee outside.
That’s right people. Timely advice to clean your steam wands.