Super cool pen!!!!!

My frend has a pen....It kinda like invisible ink in there in the pen...When you rite with it, u dont seem to see anyting....But when u flash a light on it with a light which is on the pencap, u can see it. I still can't find out the mechanism of it. My frend says tat some glow ink is put inside. But how can it be? Glow is someting when u see it in the dark, it will be seen. If anyone finds the mechanism, plz tell me....I wanna know.
But u knw....its too bad.
One can write a whole answer on their hand and then copy it from their hand by flashing the light wen the teacher is not seeing. So, it can also happen in public exams. Nobody will come to know(to those who see 'Khicdi' on POGO at 8:30, say it like Himanshu says).....
Please dont do such a thing if u get someting like this. There MUST be an awareness among the officials tat tis pen is on the loose. Plz dont use it. Tell everyone not to use it. Someting must happen. Oh! God! Only U can do someting!!!!!!!