My brother taught me to swear in Hungarian. A loud voice and some arm waving usually works.
A couple of years ago I was backpacking in the Sierras. Some clown walks right through our camp to get to the lake to pump some water. I was speechless. He came back the same way. I asked him "what are you doing walking through our camp?" He looked at me like a dog. "What do you mean?" he replied. I asked him to kindly walk around our camp next time. He said Okay like it was a brand new idea. People are not only inconsiderate, some of them are really stupid. Try to have patience with the dumb ones.