Found this interesting theory about the movie on reddit.

[Rev Doctor Abidingly]

I was browsing reddit and found this post about the big lebowski:

https://www.reddit.com/r/FanTheories/comments/3ewqlw/all_of_the_characters_in_the_big_lebowski_are/

It explains that all the characters in the big lebowski know that they are characters in a movie except Donny. It is an interesting read. The only thing I have ever seen that makes Jackie Treehorn's comical but puzzling scribble actually make sense is in the comments (I will repeat it for you):

"
[–]meowkittygorawr 242 points 2 years ago
That's why jackie treehorn simply doodles a man with a boner on the notepad, because he just needed to act like he was writing something important down.
"

Interesting. There are other related ideas in the original post.  It is admittedly an old thread (2 years) but just thought I'd share it here as it is one of the few ideas about the movie I have seen that I haven't previously heard. Just wondered if anyone else hadn't heard of this and what you guys think. Interesting read if anyone wants to check it out.

[kabbik28]

Right! Ideally you described it all, that was it!