In what issue did Loki reveal the "secret of the universe" to Deadpool?

Question

I'm doing a bit of research on Deadpool and the idea of the "fourth wall," and I've seen in multiple places that it was Loki who revealed to Deadpool that he was a character in a comic book. I've seen references to this "secret of the universe" all over the place, but haven't been able to find any information on what issue this actually took place. Does anyone have the right issue of this, or happen to know when Loki told this to Deadpool?

Answer 1

Find out everything you need to know at these links all devoted to Deadpool.

http://www.marvel.com/universe/Deadpool
http://www.marveldatabase.com/Deadpool
http://www.marveldatabase.com/Character_Gallery_Deadpool
http://en.wikipedia.org/wiki/Deadpool_%28comics%29