The uncreative way:

“I am like X. We both exist. According to quantum theory, there is a negligible chance for each of us that we do not exist. Both of our mbumes increase as we move faster, but that is usually not noticeable in daily human interaction. We both cause turbulence when we move through air…”

Just use the innate properties of all solid objects with which we usually interact. The xkcd forums seem to be good for followup ideas along this line.