My girlfriend wants me to do something out of the ordinary. What should I do?

She wants me to do something to prove my love for her. She came up with the idea that if I could stick a yellow #2 pencil up my without crying that she would truly believe that I am in love with her. I don't know if this is a good idea though because it might be extremely painful and harmful. I don't want to hurt myself and am very concerned. I don't want to disappoint my girlfriend though and I really want her to know that I do love her. What should I do? Isn't there something else I could do to show her I love her that wouldn't cause me possibly bodily harm? Please help!