What do you think about me saying bad things about my parents in a speech where I have to be truthful?
Why would you say bad things about them?
They lied to me and weren't very nice.
It's wrong to say bad things about your parents. You should be more respectful.
Nah, it's fine. They deserve it.
It's possible that your parents weren't the best, but you still shouldn't say bad things about them during a speech. I don't think people would appreciate hearing you badmouth your parents.