I go out for a run. As I come out of the apartment building I see a guy carrying a treadmill on his shoulders. It isn't a huge treadmill, but undeniably a treadmill.

I have the perfect joke, and he is a foreigner too, so it will not be wasted.

I come up beside him and greet him, he says "Hi." back.  And then..

"I think you're using that wrong."

But he didn't get it. I think he knew it was a joke. But he didn't know it was perfect.