Wednesday I was at university ... towards the afternoon, I set to return home. Just exit from, the entrance stairs leading to the stop "Cavour" Metro B: at a certain point, I see a guy go with the folder (of course a student), which - only - laughs to himself. .. I look at him, thinking "But that ride," and so - as He has not given a clear answer - I start to laugh yet I myself, but try to restrain myself ... I thought, "If someone sees me now, while I laugh to himself like a madman?"
... at that point, the lighting ...
And if the first guy was laughing because he had seen someone who laughed in turn by yourself? And if someone saw me, he too began to laugh alone?
Let us meditate on all this, guys ... The stupid smile are contagious! 
