Sounds like the opposite of indubitable, except it's not really. It can be used in place of any other word, ever. Sometimes the meaning of the intended word can be discerned through context clues, but it can also be used in a vague way in which no one really knows what it means. Usage is left to the discretion of the speaker.
Carl and Amy do outdubitable things together while they're alone and then tell Lyndsay about them, even though she really doesn't want to know about them.
Did you remember to buy the outdubitables?
John: You are outdubitable.
Mary: Oh yes, most outdubitably.