The security guard looked at our tickets and said, "Congratulations! You're at the wrong terminal!" - but so cheerfully that it took the edge off my panic.
I scrambled to find my cellphone. I called my parents, who had dropped us off. "Eep! Terminal 3!" Fortunately, they weren't far off. More hugs, a quick un-pile and re-pile of luggage, and we were at the (relatively) new Terminal 3. We had flown out of and into that terminal for our domestic flights, so I was familiar with it, but this is the first time we'd flown out of it for an international flight.
Anyway, it stuck with me a little. =) It's fun to see people having fun at work.