Attention, aspiring comedians. Here's what not to say when hosting Barbara Davis's 17th Annual Mercedes-Benz Carousel of Hope Gala, which aids childen suffering from diabetes:  fat jokes.

Why? Because Barbara's battling-excess-baggage grandson Jason Davis was at one of the front tables, that's why. And because - duh - there's a possible link between obesity and diabetes.

Excerts from Jay Leno's painfully inappropriate intro: “Scientists now believe obesity is caused by a virus. Does that mean you can now call in fat to work? “Sorry, boss. I’m can’t make it today. My ass is as big as a house. I’m gonna take two M&M’s and go to bed.”

"Dairy Queen now serves ice cream with chunks of cheesecake. Have we reached the point where cheesecake is merely an ingredient? ”Yeah,I'd like a little more cheesecake on that please.”

"Domino's Pizza is now serving a tray of brownies. Who came up with that idea? After a few slices of pizza, who goes, “Hey, I could use a tray of brownies?”

“Just look how fat our children are. Tell your kid to wipe his a** and it’ll take him an hour.”
When the audience finally groaned en masse at that final fat crack, Leno fired back, “Oh, that’s right, shoot the messenger!”

Next time Jay, better tell your writers what the charity event you're hosting is raising money for.

Hey, I'm not eating cheesecake, he is! Quincy Jones points to the brunt of Jay Leno's jokes at the Carousel of Hope Gala last weekend.
Photo Credits: (Michael Caulfield/WireImage)