Probabilities

A great *sunny* day in the bay area. I was taking the bus and kept my bag on a seat.

The *last* guy getting in the bus, at the *last* stop that was boarding people settles in an empty row next to me and feels the need to tell me:
 - "Somebody might want to use that seat".

My reply:
 - "You seem to have forgotten your umbrella."

He didn't get it.