Drinking tea with flatnate in the kitchen when strange man looms up at window, at about midnight. I was shocked and screamed then realised it was our other flat mates friend, who is staying for a few days. Let him in and calmed down, but felt a bit hysterical (also due to lots of silliness and laughing about random topics beforehand with flat mate) and then kept randomly bursting into giggles. Must have looked crazy. I feel so bad, like I've given him a complex! Don't know why I was doing it! Think it was being overtired, stressed and then the shock - he seemed bemused though.