the pen15 club

A club that can only be joined by writing "I love Pen15" on your forearm.

Person 1: Hey! Are you in the club?
Person 2: What club?
Person 1: The pen15 club!
Person 2: Cool! How do I join?
Person 1: Just write "I love Pen15" in your arm!
Person 2: *Writes* Oh shit.