The plural of ridiculous, meaning exceptionally ridiculous so much so that saying ridiculous is not enough to express the ridiculousness of the situation
If your mum came up to you and bitchslapped you to put you back in your place. That would be a suitable time to say; "That is absolutely ridiculi"
Ridiculon is ridiculous to the greatest order of magnitude to the nth degree multiplied by Chuck Norris in the rainbow land of kittens divided by the happiness of grumpy cat. This can be either interpreted in a positive or negative manner; it's open to interpretation.