I tapped the Party Pig of my last three-gallon batch of extra hoppy pale ale and it was way over-carbonated, pouring all foam. My guess is that the batch wasn't done fermenting or was infected, although it tasted fine. I also noticed the Party Pig pouch didn't activate properly. It was sort of pinched in the middle and not fully inflated, leaving a lot of head space. I sort of figured I might have a problem when I couldn't get the pouch to inflate. According to instructions on the Party Pig website, the beer should rise to the top of bottle (vertically oriented) when bleeding the excess air. If the beer doesn't rise to the top, then the pouch hasn't activated. So I took a chance letting it carb with the priming sugar in the hops that the pressure might change and the pouch might activate as the yeast created more carbon dioxide during conditioning.
Since the Pig was pouring all foam, I decided to bleed off some gas (I did this by standing the Pig up vertically so there was but air to escape when I tapped it), thinking this might reduce some of the pressure so the beer didn't pour all foam. This wasn't very smart, because the result was that I went from dispensing all foam to nothing. The pouch failed to expand and I ended up opening up the Pig, deactivating the partially inflated pouch and siphoning the beer into bottles with Munton's Carb Tabs, so we'll see how that goes. I think the issues I had with the Party Pig pouch had to do with how it was oriented in the bottle, causing to not activate properly. I think that I then pumped too much air into the bottle trying to get the pouch to activate, which may have contributed to over-carbonating the beer.