This morning I've been perusing my favorite travel writing sites and found this popular Matador article: 20 Awesomely Untranslatable Words from Around the World. Definitely worth checking out if you like words.
My two favorites:
Brazilian Portuguese – “The act of tenderly running one’s fingers through someone’s hair.”
Inuit – “To go outside to check if anyone is coming.” (I'm imagining a fur-clad head of household figure emerging from an igloo.)