A Costi is a derogatory slang term for a person, implying that they have an inflated sense of uniqueness, an unwarranted sense of entitlement, or are overly emotional, easily offended, and unable to deal with opposing opinions.
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.