Don't mess with the blow-off!

Ok I suppose there's this 1 danger to keg fermenting ... I transferred a nice chocolate stout wort into a keg, cooled it, oxygenated with pure O2 and happily pitched in 250ml yeast slurry. 18 hours later, I opened the fermentation chamber to find this.

I usually add a drop of defoamer + use a blow-off tube, but I probably was rushing through it and doing other (non-brewing) stuff at the same time. Anyway, I ended up purging the release valve ever so slowly (still got spurted at times though!) and eventually hooked it up to a blowoff tube.