Yesterday I attended a professional public speaking meeting of the National Capital Area Speakers Association. The presenter was not funny, but got laughs from the crowd.
He seriously began speaking, . . . presented slowly, . . . and kept a low tone of voice. I thought to myself, 'this is going to be a long day.' Then, without cracking a smile, a totally out of character line came out of his mouth. He was going over his material which talked about thinkers, doers etc, and said, 'A thinker is a person who is thinking about something.' The whole room cracked up. This is called 'deadpan' expression.
Deadpan expression is the technique of combining a serious demeanor with a funny line. The line typically gets a bigger laugh than the same line delivered with a lighthearted expression or smile. The contrast and surprise is what stimulates the laughter.
The most recent and famous example of this is the comedian Steven Wright who NEVER breaks character to smile. He says lines like, 'My dog is confused. I named him STAY. . . .Then I say come STAY.' A more animated and cartoonish version of this is Rodney Dangerfield who pretends to be serious about his goofy life. He says, 'I am an earth sign and my wife is a water sign . . ..Together we make mud.' hahahaha If it fits your character when speaking in public, try a little deadpan.