['I had to give a speech at work and I forgot what I was saying right in the middle.', "That's never fun.  Did you have any notes to help you remember?", 'No I did not, and everyone laughed at me. It was terrible.']
That wasn't very nice of them.  It's quite common to forget things.  Hopefully next time you remember!
I had to give a speech at work and I completely forgot what I was saying. Everyone started laughing.