Some time ago my uncle rented a boat, and while we were doing out trip around lake Maggiore, in northern Italy, we passed a boat that had the beautiful falg of Friesland hoisted at the rear. I waved at them and shouted "Friesland" pointing at the flag. At first they seemed perplexed, but when they understood they replied shouting "yeah!". We waved at each other and uped our thumbs for a few seconds until the boats were not side by side anymore.
It was a nice short interaction that they clearly didn't expect.
Did something similar ever happened to you?
Btw, the really confused people were my mom, my uncle and his family, to which I had to explain what just happened.