Let's say you want to do a thoughtful gift (say, a watch) but you have no idea what kind she would like. Enter... the Schwartzomatic Watch! You make a cardboard watch, make some silly over-the-top packaging, and tell her it's tradeable for any inferior product. Then she knows you were thinking of her, but also picks out what she wants without you trying to figure it out!

This was one of my father's brilliant brainwaves, and has been a family staple for many years now.