*I am become death, destroyer of worlds.*

Why would someone put a pen in their urethra?

Oh you poor innocent soul. Some things are best left unsaid.
- I want to be grossed out. Hit me.
A pen? Foolhardiness.
Using a sterile cylinder of metal or glass is called "sounding" and is a somewhat common fetish. I think this post is a joke, but humanity never fails to disappoint me.
- i saw a video once that used a finger with a long fake fingernail entering a male urethra, that obviously had prior visitors. no idea what the best possible outcome is.
- Glass?
  That sound like a very, very, VERY poor material choice...
Some people find the experience of sticking things in their urethra highly stimulating. Some of those people get tired of the typical thin rod, and need something... More.
I've always been more curious as to who figured this out first. Someone had to be the first to scratch the inside of their dick with a stick to awaken a whole new itch, and I find that just slightly terrifying.
- Sounder here. It started as experimenting as a child. Once i found out that i can make good feeling by touching my pp, I tried everything I could think of to make different good feelings.
  Started with lego spears and antennae around 10 I think. Also tried those little ball chains that are used as pull switches for ceiling lights. They were less fun. Nowadays I use proper surgical grade tools.
  I've got a pencil dick so the biggest I can fit is 7.5mm even after sounding for 20 years. Some guys can take up to 12 or 13 mm and it legitimately makes me jealous.
- are they resonating the thing to make it vibrate? are there some awesome frequencies? otherwise i dont understand the 'sounding' name.
It's cause the other holes are full.
Just assume they're joking and think on it no further.
Do not Google anything!
Alfred Charles Kinsey, of Kinsey Reports fame, was into sounding and at least once put a toothbrush up his own urethra... with the coarse end first.

God won't forgive me for having this knowledge

Then we will walk backwards into hell together, with heavy hearts and four middle fingers held high
- I wanna come too! Please pleaseeee
The Allfather encourages the collection of all knowledge, I am going to get stabbed with Gungnir if I spread this information to any but my fose though. Magic may be restricted to women and those who have experienced womanhood but I can still inflict psychic damage!

Sounds about right.

Skill issue. Should be doing both at the same time.

I get that's something people do recreationally and whatever, you do you, but I get the feeling you need an extent of genetic predisposition to get an object that wide up there without tearing something. Or of course the more obvious answer of the first poster was just running their mouth to get a reaction and boy oh boy did it work.

I imagine it'll stretch like any other part of your body with practice.
That being said, I had a roommate in college who you could hear that his stream was wider than most. I imagine he might be able to pull this off.
Genetics does play a role in it. I can only fit up to 7.5mm despite doing it for over 20 years.
Some guys can start there and then go much bigger.
- Genuinely curious question from someone who's not into this as a fetish but, how does this fetish give you satisfaction?
  I've had some bits of fluff get into the tip and that was very irritating and hurt for a while even after it was removed. What is the mechanism that is giving you pleasure from this activity? Enjoyment of the pain from the foreign object irritation? The sensation of the sounding rod sliding down? The feeling of it being stretched? The feeling of it being removed?

I'm not going to yick someone's yum, but goddamn I gotta say that's some impressive training. I assume that taking a piss looks like turning on a garden hose.

Probably one with a literal kink in it. The stretched out area will slow the flow vs the un-disturbed smaller diameter. Probably dribble a lot, too.

This explains the tapered end of XP-Pen

I also have a Huion graphic tablet, and this makes me not want to use it now. Like it's somehow contaminated with urethra.

Did you buy it used?
- I buy all my sounding gear used. I don't wash it either. Just lick it and wipe it on my shirt.