Glass eye

A man with a glass eye, stands at a bus stop.

As a bus arrives he bounces the glass eye on the pavement.

When asked what he was doing, he replied

" I'm looking to see if there's any room on the top deck "

you think about this joke long enough. the glass eye on the pavement, only see the side of it. but, when the bus drive away, the eye see how much room on the top deck. the man would have to miss the bus, to be claim there was no room on the top deck!