My cat is the definition of this....the whinging for food starts about 1 o'clock and it doesn't stop until she's fed.
So I guess its a chronic whinger.....one that doesn't actually stop until something is satisfied....whatever that may be....
My cat is in the kitchen, I walk past....MEOW...I run off trying to escape from the whinging......but it somehow always chases me to the other rooms of the house. If I run back past the kitchen the meowing reaches a new drawn out high pitched pleading...so my cat is a Whingypoo!
Your working with someone and they are whinging about a new rule that is considered to them stupid, but in reality is beneficial....but their constant whinging to the manager gets the new rule converted back to the previous rule....so they are a Whingypoo!