1. Fucked up 2. Going crazy 3. Not working properly 4. An all in all, true pain in the ass (this is the most all-encompassing and prominent definition)
Past tense: went longo
Etymology: Eastern Pennsylvania, 2004. Believed to have derived from the famous New Jersey bitch.
Can be used in any way appropriate to the situation.
Verb: I tried to log onto the computer, but it promptly crashed and now it is going longo on me.
Noun: My new boss is one hell of a Longo.