How to affectionately call someone who is always moaning/whinging?

I imagine the Yiddish kvetch is sometimes used affectionately. And here's some other possibilities I can picture being said with appropriate warmth:

bellyacher
codger
crab
crankypants
croaker
curmudgeon
sorehead
squawker

I think the gentlest term I could think up of, was "bear":

You have been a bear all morning! Let's be happy now.

How about "Moaner"? As in:

Come, come, don't be a moaner!

There's also "whiner", or "groucho", or "grumpy" which is very gentle:

Let's not be grumpy shall we?

Scots would use the term stropper or stroppy:

My, you're being a wee bit stroppy this morning!