Yes, blow off tube.
Get a 3-4 foot section of 1 1/4 (or 1 1/2) inch OD tubing. One end will jam in tightly in the mouth of the carboy, the other end in a juice jug half filled with water. This is just a large air lock, and it will handle all the large crap that blows out during "violent" primary fermentation.
You can leave this on for the duration, or swap it with a regular air lock after 3 or 4days.
btw, I made this about 10 years ago-it was awesome. I drank one case as soon as it carbed, the other was stored in the basement for six months. The aged case was definetly better.