I had a friend who willingly gave up a prize he won in a raffle because he couldn't get the CRAPCHA--er, CAPTCHA--right. He typed every new sequence that was displayed but still, the error message persisted. He must've made two dozen attempts before he eventually gave up. Come to think of it, it might've been a scam... But anyway, the point is, CAPTCHAs are pretty annoying.
Just give me a simple mathematical equation to solve any day, but just spare me from the CAPTCHAs, please, because they give me a serious headache.