Egging is a slang term for a sexual activity involving the penetration of a womans vagina or the anus with the aid of an egg. The egg is then allowed to hatch inside the person, so they may feel the pleasure of a young animal hatching inside of them.
This act was banned in '66 on the basis that it broke several animal rights laws and often resulted in internal lacerations to the participants.
Will: You up for a bit of egging tonight Ang?
Ang: Ooh yes, i just love that hatching feeling.