A well-known mentalism "trick" from David Blaine was when he'd ask someone to "Name a two digit number from 1 to 50; make each digit an odd digit, but use different digits", and his guess would be 37. There are only eight values that work {13, 15, 17, 19, 31, 35, 37, 39}, and 37 was the most common number people would choose. Of course, he'd only put the clips of people choosing 37. (He'd mix it up by asking for a number between 50 and 100, even digits, different digits, and the go-to number was 68 iirc.)