Otherwise the formal spelling of, redonkadonk, is derived from both redonkulous and badonkadonk; hence coupling verbal and visual absurdity together in order to portray something (emotionally and/or physically) unfathomably disturbing, amazing, or - in many cases - both.
Did I tell you about the time I saw Pat Robertson at a strip club getting a lapdance and screaming, "Hallelujah!!"? ...Yeah...Redonk-a-donk.
The name of a burger unlike any other, famous in Portland Oregon.
It's a grilled cheese sandwhich for one bun, a 1/4lb angus beef patty, egg, bacon, ham, spam, the extras (lettuce tomato etc), and another grilled cheese sandwhich for the top bun.