You hand out this pen for inspection and borrow a currency note from the audience. You make a member of the audience sign the note with this pen. You then pierce this pen right through the note and it can be clearly seen that the pen has penetrated through the note. When the pen is pulled out from the note a ripping sound is clearly heard, but when the note is inspected it is found to be intact. Pure magic, nothing but pure magic can explain this.
This is an easy to do trick that consists of only one pen, no switches or palming is done at anytime for this miracle to happen.