A young girl and her mother were walking down a street when they passed a house with the curtains open and two people clearly having sex.  The young girl says to her mother

"What are they doing mummy?"

Her mother replies

"They're making cakes sweetheart"

That night the young girl goes downstairs to get a glass of water when she opens the living room door and sees her mum and dad having sex.  Remembering what her mother had previously said about this particular activity she quite happily went back to bed.

The next day she says to her mum

" I saw you and dad making cakes last night"

Shocked her mother replies

"dont be silly you must have been dreaming"

To which the young girl replies

"but ive just licked the icing of the sofa"