After the credits to James and the Giant Peach, there’s a neat little shot of a sort of carnival-style mechanical game being played, in which the player gets to torment a little effigy of Aunt Spike.
And after Pirates of the Caribbean, you get to see that wee monkey making a bad decision.
As much as I hate to say “I heard that…” on these boards, I heard that they were drunk when they did that scene. It sure looks like they are - they seem barely in character.
Doesn’t that rock? 
Sadly, no. 
And of course, I gotta agree with silenus about Wild Things. During the credits are new scenes that happened off-screen that explain all the plot twists.
Toy Story 2 - Barbie telling patrons to put their rubbish in the bins. I was working in a cinema at the time, and people actually did put their rubbish in the bins!!
All the Pixar “outtakes” are brilliant.
The “Naked Gun” style movies all have odd things in the credits, I remember laughing at them just as a young fella on crutches started walking up the aisle passed me - I nearly died of embarrassment :o , pointed at the screen and read the credit out loud, to my eternal relief he turned around saw the credit and laughed as well …
I liked the ones on **She’s Having A Baby ** with everyone suggesting names for the baby too - I can only remember Wil Wheaton [in Wesley Crusher costume] suggesting Jason.
If you go to www.imdb.com and look at the “crazy credits” section on the left for each movies entry, they’ll give a lot of these weird credit things. Great way to kill an afternoon.
Some of my favorites have been mentioned above. The Zucker and Abrams movies almost invariably have weird credits at the end (**Airplane, Top Secret, Kentucky Fried Movie, ** the Naked Gun series). Joe Dante likes to put a “stinger” at the end (The Howling) as a reward for people who sit through the creedits.
My favorite is at the end of Veerhoeven’s RoboCop. In the legal disclaimer at the end, it says something like “…unauthorized copying of this photoplay will result in prosecution by law enforcement droids”.
A teenage slasher film had a disclaimer at the end reading “No cheerleaders were harmed during the making of this film.” (but I can’t recall which one.)