If you can adapt a joke so that it sounds as though it could just have happened to you then it is more likely to have a mnemonic impact - it will be remembered in association with the point that you wish to make.
If you feel uncomfortable, that to claim the experience would be a lie, then make it a story about a speaker in a similar situation to yours.
.Make fun of yourself
One reason that many speakers are reluctant to tell jokes that put themselves down is that they feel it may belittle them.
This is partly true. I would never tell stories that portrayed me as a drug addict or a sexual deviant. But many of the story that I use make me look human. I admit to having insecurities. I confess that I used to be disorganised. I don't hide that I have at times been embarrassed. These are feelings that will be common to a large proportion of the audience. By disclosing your shortcomings, you will build a bridge to the audience that they can travel over to reach the destination that you both seek.
.Don't make fun of the audience
While the audience may have insecurities, your role is to relieve them, not highlight them.
If you are not a lawyer and talking to lawyers, don't tell lawyer jokes! If you are a visitor to a small town, don't make fun of it!
I suggest that you avoid all stereotype jokes - ethnic, hair colour, occupation or gender based. That doesn't mean that you can't use the punch line. But make it happen to you, rather than a member of a stereotype group.
"I'm working on a great idea; White out for word processors" is just as funny as "How do you know that a [insert favourite stereotype fool] has been using your computer? By the white marks on the monitor."
A good speaker has respect for the audience. A great speaker finds ways to show that respect. Find out some things about the audience that can be used to compliment them. While many people become a little embarrassed by a compliment, I have yet to meet anyone who argued strongly that it was undeserved
