What does Back ons Backons mean?

Back ons Backons meaning in Urban Dictionary

undies that is worn, discarded then placed on again. An arse area wank...(to not be recognised incorrectly as rectal intercourse..it's just like a tit wank). The lady lies on her behalf front while her guy sits on the small of the woman back facing her feet. He pops his penis between her bottom cheeks and squeezes them together...and down he goes! Lube recommended.