I got tonnes

You know that saying - I've got shedloads (of, for example, books, or something) - in my head I always imagine enough to fit in a shed (its not an infinite number but it is a lot). Someone today was saying they have a problem when the phrase is used because they can't decide whether the shed is a noun or a verb. I've never before realised that actually the use of shed in this phrase is a verb. It doesn't refer to enough to fit into a shed - it refers to an  amount that has been shed from a lorry. A shed load. Doh. BIG doh. I astound myself sometimes. How have I got to be 40 and not realised this yet?