A NOVA (No Obvious Value Added) is a person who in any social event adds no value to any conversation or activity. They are boring, dull and no fun to have around. There is also such a thing as a Super NOVA.
Man why did you invite Susie to the Super Bowl party, she's such a NOVA (No Obvious Value Added). She just sat there and said nothing with that blank look on her face see whole time. Also see Super Nova