Diacetyl

Diacetyl is a bane to many brewers. It's a natural by-product of fermentation and gives butter is distinctive buttery flavor. At low levels it provides a slippery mouthfeel, and higher levels, it's gross. Trust me.
Usually, yeast will produce diacetyl and then eat it up. Usually.
I underpitched (didn't put enough) yeast in my last Centennium Falcon IPA.
Remember, this was an experiment using harvested yeast from some Bell's Two-Hearted Ale, and a stir plate. So I shoulda made more yeast, but I didn't.
This underpitching may have caused my diacetyl issue, OR I may have a bacterial infection. I'm really hoping it's the former.
So the beer fermented out to a nice Final Gravity of 1.012. And it's nice and hoppy, but the butter is just icky.
After some research about whether I can save the 5 gallons, or if I should just dump it down the basement utility sink, I've run across some suggestions to do a "diacetyl rest" on it. Usually lagers will get a 24+ hours (@ ~58F) diacetyl rest after secondary (or even primary) fermentation is complete. I'm hoping that a rest will allow the yeast that are still in the keg will be able to wake back up and eat up some butter flavor.
Keep your fingers crossed.