This notice on a train ticket vending machine warns people that gum or other substances may have been placed intentionally in the coin return to rob them of their money. Most people are in such a rush that they probably don't count their change, and after they have gone through the turnstile, someone will place their fingers into the machine and pocket the blocked coins. Some of the machines even let you buy a ticket with a 10,000 yen note, so any change over 1000 yen will come out of a separate bill return. Now if I could only find a way to block that, I could quit my day job.