#233: A New CAPTCHA Approach

XKCD comic, described below.
Transcript

To complete your web registration, please prove that you're human: When Littlefoot's mother died in the original `Land Before Time', did you feel sad? [[radio button]] Yes [[radio button]] No (Bots: no lying)

They'd use that Futurama episode with Fry's dog, but even spambots cry at that.

ExplainOriginal