Contrary to whatever your reading the original word came from modern poker. The word is a combination of the 2 root words "Ridiculous" and "Donkey". The ridiculous comes for the bad judgment at a poker table and the Donkey is what poker players call other poker players that apply bad judgment. Hence "redonkulous" ridiculous donkey.
Why would call that bet with a 3 outer? That's redonkulous.
Having the qualities of being ridiculous, but to a greater, perhaps exponential, degree. Marked by crazy ass qualities that make you laugh sooooo hard. Fucking hilarious.
Johnny Cash relapsing into drug use because his pet ostrich kicked him severely (boot party) in the 1980s (AD!!!). So an ostrich makes him shoot up?! Ridonkulous.
Redonkulous is a way of explaining something that’s more ridiculous than ridiculous. Like how something could be insanely weird or awesome. This could also be the name of some YouTubers.