Ashlee Simpson is still remaining tight-lipped on her pregnancy.

On The Ellen DeGeneres Show (airing Thursday), the talk show host asked her flat-out if she were expecting.

"Well, that has been going on for quite a while. That is definitely something that I choose personally not to discuss except for the fact that maybe…."

She then added, "Do I look like I had 10 cheeseburgers or something … because I don’t think I do," before standing up.

Pointing to a photo of Jennifer Lopez, DeGeneres then asked, "You’re not going to keep this answer up as long as this woman did...."

Laughing, Simpson replied, "No, I’m not. I swear. I promise you that. I give you my pinky on that."

The singer told DeGeneres her fiance, Pete Wentz, was "the greatest, awesome."

How did she know she was ready to wed the rocker?

"I don’t know," Simpson said. "Maybe when his jeans fit me ... I decided we could wear the same clothes.

"There were lots of moments," she added. "But every time he would leave [on tour], I would cry, so we had this inseparable relationship."