The secret ingredient to successful public speaking is humour.
Humour is what gives away a truly skilled public speaker.
The ability to make your audience laugh is the ultimate goal in becoming a successful speaker.
Usually people who deliver a speech in front of large audiences or in front of the camera tend to focus mostly on themselves. On the message they have to convey.
On how not to be nervous, sound incoherent, look good, smile, be smart, charismatic and so on.
Making people laugh is the opposite of all of the above. It means to shift focus to the audience instead of constantly being self-preoccupied.
Slipping a joke during a speech is the most efficient way of actually getting to your audience.
It means that the speaker is kind enough to allow the audience to relax for a few seconds.
That he is not selfish.
He doesn’t want to hold the floor.
It's a way of showing respect to the people engaged in your presentation.
Besides, you don't want your audience to lose track of the flow of information but neither you want to exhaust them.
A good joke enables people to take a break without actually taking a break.
Humour also means that you really want your audience to have a good time.
You don't just want to give a speech.