It happened to me. What was your worst travel mistake?

I'm sure you have heard those travel stories … Like the executive who missed an important client meeting in Japan because he didn't realize his passport had to be good for six months after his trip. Or the sales person who booked tickets to the wrong city and had to rent a car and drive all night. Or the guy that forgot to book a hotel and the only free room for miles around was the $600 penthouse suite. (These are all true stories. I know the people they happened to.) Depending on your personality either you think "I'd never do that!" or "I hope that never happens to me!"

Well, it happened to me. I always figured if I was going to goof on my travel plans, I'd book a ticket for the wrong city. But no. I just booked a ticket to Brazil and didn't apply for a visa. The airline kindly informed me of my mistake the day of the flight.

What was your worst travel mistake?