I was in my friend's house in the courtyard doing something for the university, I was wearing a sleeveless T-shirt, we were trying to solve a physics problem. A bird flew over us and a feather fell, my girlfriend grab it and said "oooh what a beautiful feather isn't it?", I said "yes dear". I put my arms over my head trying to figure out the problem, I was getting angry because I couldn't solve it, then my girlfriend said "Come on don't get to presure on yourself, here some little tickle to calm you", and with the feather she tickle my right armpit, I laugh and put my arms down, and she said "see? a little laugh calm you down". I look at her and said to her "I guess you're right" then we kept thinking about the problem 'till we figure it out finally.