A person who is foolish and brings rejection and embarrassment upon themselves in full view of their social group or the general public. This phrase was first coined by a nerd in Australia, and is a conjunctive of dumb and jumbotron.
The HUGE display screen typically found at sporting events. It shows game/player stats, scores, replays, advertisements, etc to the crowd.
Jumbotron is actually a Sony trademark name, but the word is used to refer generically to any gigantastic LED screens like it.
At a basketball court, the jumbotron might be about 11 feet wide, but in a football stadium, it'll probably be more like 33 feet.
12 step recovery jargon referring to someone new who talks about how great life is, now that they'resober. Usually meaning that the person is out of touch with reality.
The new guy seems pretty happy for a dude who has no job, no money and no family. He must be on a pink cloud.