[Curmudgel]

Perhaps that's what the term means to the author. To others, it's a synonym for a drunkard or alcoholic and has nothing to do with flirting.

[prawn]

Maybe it's an affectionate way of saying boozehound, as you might needle a friend.

[Curmudgel]

It's pretty clear from the smiley in the title that he was just teasing her. I just found it odd that he would write it in the title of a blog post meant to be read by thousands of strangers. It's like shouting some bit of raillery at your friend across a crowded public plaza.