Be a brah...just say fu buddy, I'm riding and if you want to bowl in the gutters, oh well...otherwise tell him to get a lesson from a hot boarder chick
It's harsh, but it's true. You have to commit in order to progress in snowboarding. If you're not willing to commit, you won't improve. Tell him eating shit is just part of the learning process, and that once you get your frontside turns down, it gets tremendously easier and less painful.
PowderHound and TreeNinja