Today my friend's gf challenged me to an arm wrestling match to prove to her friend that she was as strong as a man now. She's started doing karate a few months ago and she never stops talking about it. She's super proud of the results she achieved. Anyway, they asked me because I happened to be closest guy in the friend group to her. I thought it was a joke and so I put out my arm while barely applying any pressure, but she was taking it seriously. She was clenching her teeth and holding her breath, and her face started turning red. I felt nothing... but I felt really bad for her and didn't want to humiliate her in front of her friend so I pretended to struggle and lost.