Unridiculous is when something is not ridiculous, funny and is just plain serious. However, in its opposivity, it is ridiculous in the way it sounds thus making it a double-entendre.
Megan Fox is so hot, it's unridiculous.
“Unridiculous” is a portmanteau of “unbelievable” and “ridiculous” coined by Clint D. during a frustrating phone conversation with a Chinese restaurant over an incorrect order. It refers to a combination of frustration, severe disbelief, and confusion. (The term may have originated from "UN-believable," a common saying of a coworker with a long emphasis on the first syllable and with similar meaning.) Mimicking this confusion started as a joke, but the term has come into serious usage among his ~100 coworkers and possibly beyond.
I have to work Saturday AND Sunday? This is unridiculous.