VIDEO: Casey 'Splains How She Sang Herself To Safety

Casey's fear of heights is pretty well documented by now, so we weren't exactly shocked when she started shaking like a leaf during this week's high-altitude mission on The Ruins. We were, however, surprised -- and impressed! -- to see the tiny, trembling Challenger stick it out and finish (er, eventually), despite all the heckling, yelling and snickering coming at her from the sidelines. Oh, and FYI, that's where "I've Been Workin' On The Railroad" came in. Apparently, Casey calmed her nerves by belting out the first song that popped into her head. (Hey, just be grateful it wasn't "Cotton-Eyed Joe" or "The Macarena.")