.

Sheldon: So, if a photon is directed through a plane with two slids in it and either slid is observed, it will not go through both slids. If it's unobserved, it will. However, if it's observed after it's left the plane, but before it hits its target, it will not have gone through boths slids.
Leonard: Agreed. What's your point?
Sheldon: It's not a point. I just think it's a good idea for a t-shirt