Khloe Kardashian Not Pregnant, Despite 'Dad + Mom' Post with Tristan

Khloe Kardashian and Tristan Thompson are calling themselves "Dad + Mom" -- but DON'T FREAK OUT ... they're not preggo!!!

The reality star posted some pics from her surprise 33rd bday party from over the weekend -- including an image of her and TT kissing with the caption, "Dad + Mom."

Khloe has recently talked about having kids with Tristan on "Keeping Up with the Kardashians" -- saying, "He wants to have about five or six kids with me and that’s lovely. We could start at one and we could grow from there."