A play on "inept", or "ineptitude". The word is used to describe someone who is incompetent, stupid or an idiot.
Can also be used to refer to someone who takes credit for another person's idea after the fact, or only talks about things and never actually does them because they are too incompetent.
"The Australian Greens are such fucking nepts. They do nothing and take credit for other parties' policies because they don't know what they're doing and think taxing corporations is easy to do without them fighting back."
An expression used when something goes horribly wrong but you are somewhere where it is inappropriate to use the term "fuck" or any other vulgar therm.