If you make a joke, telegraph it. If you're not sure the joke will land, cut it
I would also say leave an obnoxious amount of time for laughter, I know at my demo day pitch I cut laughter short because it was hard to hear and I was fairly anxious
Timing for laughs are tricky. You need to wait long enough such that you don't cut off the laughter, but cut in soon enough that there isn't an awkward pause.
I have no experience of pitching anything, I'm just a dev but...
Laughs?? Why are laughs even in the script? This is a business deal right? One day I'd like to start something myself, and I guess I hoped that shrewdness, business acumen, techical chops, idea-originality, those would be more vital parts of a pitch. Do we need to make investors laugh too? Genuine question.
Jokes are a good way of managing tension and encouraging rapport with your audience--if they're laughing with you, they're having a good time, and if they're laughing because of something you've said on purpose, you've got a bit of control. It's a good way of staying at-ease in front of dozens of people.
EDIT:
Luckily pitching and presenting IRL is much easier (and less harsh) than cracking wise here on srs bsns HN. If you can get away with jokes and upvotes here, you'll be fine at any venue in person. :)
I would also say leave an obnoxious amount of time for laughter, I know at my demo day pitch I cut laughter short because it was hard to hear and I was fairly anxious