Rat up a rhododendron

[Renato]

really fast. So fast, in fact, that you wont believe how fast it happened. Often used to describe the speed at which a male penetrated a sexual orifice and began intercourse.
This term, among others, came into wider use in [the 1970s] largely through the Australian-originated slang of the [Bazza] Humphreys character who was then featured in the British [Private Eye] magazine.