Jon Gosselin Cheats on Kate Gosselin's Birthday

Jon Gosselin "cheated" on Kate Gosselin's 34th birthday because he spent the day with his 23 year-old side dish Deanna Hummel.

Jon Gosselin also didn't buy Kate birthday present while he was out with Deanna. Does that make him a pig, or someone who doesn't wanna rub his relationship in his mistresses face? The world will never know. GASP!

Kate's birthday was March 28 and Deanna Hummel joined Jon at a festival where he "curled up" on Deanna and drank free Budweisers. So scandalous!

As the night wore on, Jon and his hard-partying pals began "reeking of pot. I know that the kids he's hanging out with like a little herbal substance."

Jon and Deanna first met while partying at local bar Chill Lounge near his family's $1.1 million home in Wernersville, Pa. "Jon was a dirtball," Elyse Motague, the waitress Jon asked to have send Hummel a shot by way of introduction.