"If you can't tell a spoon from a ladle, then you're fat!"

This quote by Demetri Martin is a funny method of stating that if you do not understand the distinction in between a spoon and a ladle, then you do not have knowledge or experience in a particular area. It could be interpreted as a metaphor for someone who is not knowledgeable or informed in a particular subject. It might also be interpreted as a joke about someone who is not extremely watchful or has difficulty distinguishing between two comparable items. In either case, the quote is implied to be funny and easy going, rather than a serious criticism. Eventually, the quote is an amusing way of stating that if you don't know the distinction in between a spoon and a ladle, then you might not be as experienced or knowledgeable as you must be.