I laughed at this

A Canadian, a American, a really hot chick and an old lady are on a train.

They're sitting there quietly untill the train enters a tunnel, and for some reason the lights dont come on.

Now its a long tunnel and after a few minutes of sitting in the dark, everyone hears a LOUD "SLAP!"

Sure enough when the train finally exits the tunnel, the American has a huge red slap mark on his face.

Now the old lady sees this and thinks: "That poor young lady, That American must've grabbed her knee and she slapped him"

The hot chick sees the slap mark and thinks: "That poor old lady, that american must've wanted to grab my knee but grabbed hers, and she slapped him!"

The American is thinking: "That DAMN Canadian must've grabbed the hot chicks knee and she slapped me by mistake"

The Canadian meanwhile is sitting there thinking: "Boy I hope there's another tunnel so I can slap that American again"