How we change what others think, feel, believe and do
It is a strange phrase, isn't it? 'Politically correct'. What it really means is doing something without insulting, upsetting or otherwise hurting other people. Just incorrect, really.
Using non-PC humor is a dangerous thing these days. Even if people laugh, they may not consider you very bright for using such social transgressions. If you break the rules like this, how else might you break it? If you laugh at other people's misfortune, will you laugh at them when they are in distress?
Being PC with humor is not always as easy as it may appear: many jokes are at the expense of somebody or other. Many countries have a 'scapegoat' nationality or locale, whose people are taken to be all congenitally stupid and against whom jokes are told to show their total lack of intelligence (and, by implication, the intelligence of the contrasted people). For example, the English tell jokes about the Irish. But then the Welsh tell jokes about the English. In parts of America people such as Poles act as the butt-end of stupidity jokes, whilst Poles tell jokes about the Russians.
The general principle used is typically exaggeration, where you take one characteristic of the target population, preferably where there is some element of truth, and blow it up out of all proportion. Thus you get jokes about mothers-in-law, lawyers, politicians and so on.
A strange aspect of humor is where we laugh at a person slipping on a banana skin or otherwise suffering a misfortune. This has been used in a whole branch of visual humor, often called 'slapstick'.
The Germans even have a word for the pleasure we feel when others suffer a misfortune: schadenfreude, which often interprets as 'there but for the grace of God go I'.
This humor can fall on its face when other people have suffered the misfortune being laughed at.
Humor is often used as an incisive weapon. A sarcastic or cynical remark can have a withering effect on other people.
"And tell me, Professor Jenkins, do you always comb your hair that way, or is it just the way the wind is blowing?"
It can be used gently too, and even a simple question to an overblown comment can take the wind out of arrogant sails.
"I just bought a very expensive stereo system."
"Oh. How does it go with the wallpaper?"
Some people would say never, but there are some occasions where deliberately being non-politically correct is effective at changing minds.
As a negative example
You can deliberately be non-PC in order to show how wrong it is. A tricky way of doing this is to demonstrate bias against the people to whom you are talking. So if speaking with a group of college professors, you could tell a joke about how all professors are so unworldly they can't even tie their shoelaces.
Be careful with doing this. You could annoy them so much they miss the point. Make the joke gentle and not too offensive.
To show yourself as 'one of the gang'
Deliberately being non-PC can also work to build your status when you are talking with people for whom being non-politically-correct is either the norm or has special significance.
Cultural groups often signal their membership and commitment to the group by telling each other jokes about out-groups. Thus engineers tell jokes about marketers or HR people (see Dilbert), school-children tell jokes about teachers (and vice-versa) and so on.