This one is for the folks in Poland who take pleasure in a surprise. All you need is one of those ubiquitous black domofon keypads and maybe a good memory for numbers. Enter the digits 058758575130 in sequence and you will hear a familiar melody, possibly to the delight of passersby, who will surely think that you must be a fascinating person. Don’t worry about accidentally ringing, say, apartment 058—just use the disconnect key after the last number.

Where did I get this? A few years ago I was that impressed passerby when young man was showing off for a lady friend in Warsaw’s Różana. Neither of them minded when I swooped in with my questions, and I’ve been entertaining friends and strangers with this one ever since.