Similar to an ultimatum, but one where the answer is truly "maybe" to both possibilities. In most cases an ultimaybe is much harder to deal with than an ultimatum due to it's confusing unanswerable nature.
Person A: You should really go to the dance with your girlfriend instead of that really pretty girl you're not actually in a relationship with.
Person B: But... I could be...
Person A: Doubtful.
Person B: Huh... this is an Ultimaybe. I'll never know what the right choice was, ever.
When you think you are giving an ultimatum, but there are really a whole lot of answers you willaccept.
Person A: "I totally gave Bob an ultimatum yesterday when I said that he has to choose between me and his girlfriend, but he said he chooses us both, so we're all good."
Person B: "So it's really more of an ultimaybe."
Ruler of Lake Titicaca. Rumored to have a bunghole that gets very angry if it does not receive toilet paper. Cornholio the Great is often seen walking around with his shirt over his head and his hands in the air, chanting songs about his power, and his bunghole.
"I am Cornholio! You do not want to face the wrath of my bunghole, for I need TP!"
Butthead: Shut up, Beavis! (uh huh huh huh)
Beavis: Um, okay. (heh heh heh heh).