A so-called Australian sexuality expert has been ridiculed after saying parents should ask for their baby's permission before changing their nappy.

Deanne Carson was being interviewed by ABC News when she said teaching a "culture of consent" should begin from birth.

She said to tell babies, "I'm going to change your nappy now - is that okay?" and then wait for a response.

"Of course a baby's not going to respond, 'Yes mum, that's awesome - I'd love to have my nappy changed.' But if you leave a space and wait for body language and wait to make eye contact, then you're letting that child know that their response matters."

Parents know how uncooperative babies can be, and so do Twitter users, who laid into the pink-haired educator.

"If a child has a dirty nappy then their parents should change it because that's part of caring for your child properly - not because their child granted them permission," said @Kezzabelle5.