I was honestly just pondering this earlier in the week. I brewed a gallon of MO/EKG in a glass jug. I always use a blow off in those jugs, and generally need it. I filled this one quite a bit higher than I normally do, anndddddd its just a regular boring krausen. I had extra stoppers and tubes ready and set aside for an inevitable clog, too. If I'd put an airlock into it, I bet it would have been embedded into the ceiling.