Little on the walls. Was keeping an eye on it last night until I took a bunch of NyQuil and went to bed. Lid still MIA after putting the tube on and cleaning up a bit
Found it!
I would have put a blow-off on earlier but I was looking forward to drinking the airlock vodka and thought I had enough headspace.....Next time
Just had mine almost do that in a 6.5 gal carboy. My lid stayed on and it just sprayed the walls and pooled around the carboy. Had some pressure built up and spit in my face when I pulled it off to put in the blow off. At least it tasted good. (I know....."thats what she said")