Someone might ask you to join their pen club, but they already have 14 members so you can become 'pen 15'. They will write this on your arm so it will be defined who you are! Never turn down someone who asks you to your pen club
on your hand, then ask if they wanted to join the pen15 club. it worked best if you had a bunch of people do it. then you would get them to go through the secret ceramony where you would write "pen15" in the so that it looked like you wrote "Penis" and you would point and laugh. best done with sharpie marker.
When a girl has taken dick with out a condom, the guy came in her. And she liked it, the guy writes pen 15 on her hand. She is now part of the pen 15 club.
John had to take my hand and write pen 15 on my hand at the dentist. Then the receptionist said, "ah huh, pen 15 club." Then i ask what that mean. He tells me then i smack him.