I recently switched to my glass carboys as a unitank in order to avoid contamination during transfer (I've had a lot of suspect batches). So now I'm noticing that, after sanitizing the carboy with StarSan, the hole is rather slippery and any internal pressure, be it from the foam of the freshly-poured wort or the pressure from yeast activity, pushes the dang carboy cap and airlock out! I'm sure many have experienced this problem and I'm wondering if anyone has any tips on how to prevent this from happening.