It's been awhile since I have seen this flick but here is a plot synopsis:
The 2 main characters are a couple guys in their very early 30s. They are both geeks to the nth degree. One guy works for a low-budget film company, the other is your general "still searching" type. I don't think he has a real job, and his house is full of geek collectibles.
Anyway, these two guys see William Shatner playing a "Washed Up" Shatner in a book store. They befriend him while Shat is looking at porno. Shat initially doesn't want to have anything to do with them, but when he learns one works for a film company, shatner pitches a 3 hour Rap version of Julius Caesar, where Shat plays all the parts (one man rap show). Comedy Ensues.
great flick!