Perhaps Fergie is studying to be a lactation consultant? The Black Eyed Peas singer, who's pregnant with husband Josh Duhamel's baby, stopped by E! to talk maternity style with Fashion Police's Joan Rivers -- but somehow ended up demonstrating breastfeeding tips while sitting on the 79-year-old host's lap!

The expectant singer Instagrammed a shot of herself poised on River's lap and staring demurely into the camera as an eager Rivers pretends to nurse. She captioned the picture "Taping 4 tmrw's #FashionPolice. Breast feeding class w/ #JoanRivers."

PHOTOS: Fergie's baby bump style!

Fergie has clearly been having fun with her pregnancy since she tweeted on Feb. 18 that she was expecting her first child. At the Kids' Choice Awards on March 23, she and Duhamel even wore matching polka-dotted bandage dresses and baby bumps for a skit. And on Chelsea Lately on April 4, Duhamel revealed that his wife stipulated that he'd watch the birth only from the waist up.

VIDEO: Fergie shows off her bump at Kids Choice Awards!

"I will be there. She says that I can't be anywhere below right here," he explained, pointing to his chest. "You know, because some women get nervous about the actual birthing process."

"But for me," he added. "It's a beautiful thing."

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This article originally appeared on Fergie Pretends to Breastfeed Joan Rivers: Picture!