Via Daringfireball: Cooper's One Free Interaction

In school, we used to talk about designing the perfect fidgeter's gadget. It was basically a product with no specific function except to be fun to play with, like a paper weight, except with even less utility. Various designs included ball-pen clickers, ratchets, pushbuttons and sound effects. The Free Interaction goes one better by appending something otherwise functional with a little extra humanness, i.e. a reason to love it beyond its inherent purpose. On men these are called "biceps" and on women they're "boobs."