The best jokes are offensive.
Analyze it.
Is it completely neutral? Probably not.
What about word plays, they are not offensive eg.
'Why did the chicken cross the road? To get to the other side'
The chicken wanted to die and reach the 'other side' (ie. heaven) - but this is offensive to people considering suicide, you are calling them chickens!
Hell even chickens, if they could understand humans, would take offense because we use their name as the word for 'coward'.
Ok what about other word plays:
Knock knock Whos there? Orange Orange who? Orange you glad I didn't say banana?
However, that's not a very funny joke.
Tell it to a person who's enunciation of the word "aren't" is close to "orange" or a person who has bananaphobia (yea, they exist), and it gets a little better.
Puns in themselves are hard to laugh at, but once you attach a certain context, they can become really funny. Usually that context can be found offensive.
'Supercollider?' - Not funny
'Supercollider? I just met her!' - Funny, offensive
Is this funny: Arn-Old
How about now: http://thechive.files.wordpress.com/2012/06/funny-captions-0.jpg?w=500&h=595
The best jokes are offensive, stand up comedians are notorious for it. However because of the nature of their work, no one complains, everyone knows they don't truly believe what they are joking about.
Or do they.
Remember Michael Richards (aka Kramer from Seinfeld) before the whole Racist Tirade[1] if he made a simple black joke, people would laugh at it. Not anymore.
Carlin said it best[2], context matters, at the same time though, if there is no hint of offensive in the joke, it loses the taboo aspect which makes it funny.
Sitcoms; Miscommunication between actors leading to funny situations, achieved by implying one party was stupid or situational stereotyping (eg. Fonzie), it all ends up giving a sense of superiority (from the audience) which ultimately creates the 'funny'.
What does that say about human sense in general, are we creatures that only find happiness in the misfortune or degrading of others?
Also, is there a truly neutral joke which is actually funny?
[1] http://www.youtube.com/watch?v=6Pksx_IAHDE
[2] http://www.tmz.com/2006/11/20/kramers-racist-tirade-caught-on-tape