They were going on a yeti-viewing-party. That was true, and Lex got a happy nod-nod-nod when she said it. It wasn't really a fact about yetis, but it was a fact about Mo, who was basically 15% yeti. As close as most people were going to get, y'know?

Mo flipped open the book, but he already knew loads about the yeti, and it didn't take him long to shut it and lean forward on his desk, giving the professor a long, solemn face. "Yetis are very protective of their young, which contributes to their reputation of being bloodthirsty and dangerous. Some speculate that missing hikers and mountain climbers in the Himalayas who were reported to have succumbed to the elements were actually attacked by a yeti. I say... that might be true, but they probably deserved it for roaming into the yeti's home uninvited."