We took a train to the Mutenice wine festival. We ended up sitting very close to a bunch of drunk college students who were chugging wine straight from the bottle and being obnoxiously loud. Then we noticed this sign on the window. At first, I didn't realize what it meant, but my hubby guessed that it was the warning for those drunken passengers not to throw away the bottles out of the window. Certainly they looked too drunk to care about anybody or anything else. I wonder if this is a Czech specific sign.