What is Granny Dip?
1.
A Granny Dip is when the penis is removed from the vagina during sex, either accidentally or on purpose, then quickly inserted into the anus and then back in the vagina to continue with straight sex.
"I was banging her pussy hard till I felt like a bit of a granny dip; she strongly objected."
or,
"Granny dip my arse, dip it, DIP IT!"
See