Why would you say that?

Yesterday we had a Mongolian friend come by.  She has been a Christian since 2005 and is really trying to follow Christ in her daily life.  She speaks some English, but it is pretty interesting how our conversations go from English to Mongolian and then back again.  Anyway, as she was leaving we were discussing some of the different sayings in Mongolian and also English that we always say, but don't really know where they originated.  Mongolians say "Going to the Salt" when they are going to sleep, I wanted to know where that came from.  Then she said, "Well, why would Americans say 'I am hungry enough to eat a horse'?  Just eat some horse!"  They eat horse here all the time, so that isn't an extreme hunger saying for them......It's all how you look at it.