Given to young people as an exercise in organization.
The pen would have a mechanism that registers it's with
the same owner every time a code is put into it. A
would show how many years that owner has managed to
keep it in their possession.
This is not totally frivolous and silly,
(just sort of). Given
a child when they enter school, it would begin to instill
them some measure of organization. If the person can
keep track of one of the single most used and tossed
tools made by man, they may be able to keep other
organized as well.
This would appeal to nerds and geeks who would proudly
announce to the attractive gal at the bar "M'lady, I've had
this pen since my grandma gave it to me on my 5th
birthday." right before she had to go to the "lady's room"
from whence she'd never return.
The code would be tapped into a series of two buttons
on the side and would possibly replace spinning or
tapping as that thing you give your hand to keep it busy
while you're reading the document to be signed or
otherwise written on.
Of course there's a low tech version of this that just has
a date printed on it.