Actually it is a weatherproof paint pen. I also had a yellow one for DH's bike. I actually left the pens there since so many others wanted to borrow them. I am not sure how many people wanted hot pink, but I am sure the yellow was used frequently.
Also, when Floyd signed my bike he said "who is this guy?" when he saw my bike. I professed complete ignorance and told him I had never heard of any one by the name Lemond!!