A malaprop is an absurd misuse of words. It can be from words that sound alike (sadistic and statistic) or from explanations that don't make any sense. You can use these on purpose as a humor technique during your public speaking engagements. Consider some of the classic examples below:
Casey Stengel
The great comedian Norm Crosby, who is best known for appreciating standing ovulations when he performs, has made a living out of the ingenious misuse of words. In real life though, malaprops are usually uttered by people who don't even realize their fox paws.
A flexible public speaker who was truly in touch would have:
"f Mark Twain can spell a word in more than one way, I should be able to say a wrong word at the right time."
If you don't like that one, make an ad-lib up on your own. To make effective presentations, you must appear human to those you speak to. Humans make mistakes. That's part of life. As Archie Bunker says, 'Case closed, ipso fatso.'