What is it with men and them naming their genitalia?

In all honesty, can someone please enlighten me what is with Men and their genitalia? I grew up hearing "manoy" "junior" "jun-jun" when men refer to their genitalia.

Back in 2010, a friend of mine was discussing a topic on post modernism and "naming" in front of the class that led to a topic about how men treated their genitalia. I was seated at the way back section of the room, when...

"Not only that, men also give names to their genitalia..."  I accidentally blurted out, while flipping through the pages of a fashion magazine that I was secretly browsing in class.

The room fell silent, as all eyes turned around and stared at me, as I fell silent and embarrassed that I caused a small scene. I wasn't the one reporting and here I am, genitalia-speaking at the back of the friggin' classroom.

"But...that's what they said." I continued, trying to pick up my small piece of dignity left. After all, it's my first semester back in graduate school, I was trying to be proper.

But really. I remember one of my favorite movies, How to lose a guy in 10 days, showing Kate Hudson (Andie)  in a scene with Matthew McConaughey (Ben), and Kate's character was naming Matthew's thing, with "Princess Sophia".

Screen caps from the net

Andie: Does Princess Sophia want to come out and play?
Ben: Who's Princess Sophia?
[Andie points at his crotch]
Andie: Little, big, little, big... I don't know... we will find out!
Ben: You can't name my member... Princess Sophia.
Andie: Yes, I can!
Ben: If you are gonna name my... member, you have to name it something hyper masculine. Something like Spike, or Butch, or Krull the Warrior King!

My guy friends went to Baguio and came back with a pasalubong for me:

So thoughtful of you guys! Tsk tsk. 

Actually, I already have a feeling that this is what they will get for me.

I love my guy friends, I think I've been hanging out with them too much that's it's gotten to a point that I can read (even though I don't want to) the green jokes and the read between the lines. Now I'm paying for it because they claim that I'm the malicious one. One even said if I'm still a smoker, I would surely get the ashtray version. Something like this that I found on the net:

Image from google

I wonder how men feel putting out smoke from their cigarettes with the replica of their "thing" staring back at them?

Now back to the question. What is really with men and their genitalia?