Some quotes from here (
http://www.sciflicks.com/spaceballs/quotes.html)  
 Colonel Sandurz: It's Mega-Maid! She's gone from suck to blow! 
 Minister: Dearly beloved, we are gathered here today to witness Princess Vespa, daughter of King Roland going right past the altar, heading down the ramp and out the door! 
 Dark Helmet: Before you die there is something you should know about us, Lone Starr.
 Lone Starr: What?
 Dark Helmet: I am your father's brother's nephew's cousin's former roommate.
 Lone Starr: What's that make us?
 Dark Helmet: Absolutely nothing! Which is what you are about to become. 
 [Watching "Spaceballs: The Movie". They reach "now" in the movie.]
 Dark Helmet: What the hell am I looking at? When does this happen in the movie?
 Colonel Sandurz: You're looking at now, sir. Everything that happens now is happening now.
 Dark Helmet: What happened to then?
 Colonel Sandurz: We passed then.
 Dark Helmet: When?
 Colonel Sandurz: Just now. We're at now now.
 Dark Helmet: Go back to then.
 Colonel Sandurz: When?
 Dark Helmet: Now!
 Colonel Sandurz: Now?
 Dark Helmet: Now!
 Colonel Sandurz: I can't.
 Dark Helmet: Why?
 Colonel Sandurz: We missed it.
 Dark Helmet: When?
 Colonel Sandurz: Just now.
 Dark Helmet: When will then be now?
 Colonel Sandurz: Soon. 
 [nurse exits]
 Dark Helmet: I bet she gives great helmet. 
 Dark Helmet: WHAT? You went over my helmet? 
 Lone Starr: So, Lord Helmet, at last we meet again for the first time for the last time.