Because I went to engineering school, and then became an engineer, I developed the habit of always having a pen on me. There were far too many occasions where I needed to write to not carry one.
Because of needing to label samples at work, shortly after graduation, a "magic marker" joined the pen as a permanent pocket partner.
When I arrived at parenthood, the need to put names on various labels and toys substantiated this need.
Here is where I need assistance.
Multiple times when interacting with others in non office public locations, someone has said:
"I need a sharpie."
At which point I pull mine out and hand it to them.
At this point, the person who was looking for one invariably, incredulously, says some version of:
"You always carry a sharpie with you? WHY!!??!"
I'm not sure if my reply should be:
"For just such an occasion, doofus!"
"Because pinheads like you don't!"