I'll go with thirst....I tried a few options for getting commercial beer into a keg, but nothing panned out.
I was wanting to both learn about carbonation, as well as test my system for leaks etc, so I went with a keg full of water. Chilled it, attached the co2 at 30psi, and rocked it under foot for 10 minutes or so. Backed it off to 10psi, and voila, soda water. A bit undercarbed after just the rocking, but carbed nonetheless. Left it at 10psi for a day or so, and it was perfect. Kids are loving the instant fizzy drink machine dad has on the back deck. Bit of cordial in a cup, fill with soda water, and they told me "you're epic dad". Ok they might have said "that's epic dad", but same same.
Even made the missus a non-alcoholic version of her favourite elderflower & lime cider on a hot day recently, and got the nod of approval. Mind you I told her the whole setup cost about half what it really did, and she still gave me that "do you really need that?" look...so I still have some work to do there...
h34r:
My Kolsch is on day 6 of fermentation, and almost at FG, so it should be in the keg by Sunday night for lagering. Will probably taste ordinary for the first few weeks, but at least I'll have beer coming out of a tap! Will brew a hefe on the weekend so that should come up to speed pretty quickly.