Blow off tube diameter

So, what diameter tubing do you guys use for your blow off?

For my old system, I had larger tubing that I'd use. Just out of habit I guess. It was the same size as the mouth opening on the carboy and fit snugly in place. Now, putting together the new system I'm using a Demižon (for anyone that doesn't know, it's basically like a carboy just a different shape) instead of a carboy and it's got a 4 cm opening. So, the old tubing is out. But giving half a second thought, just figured I could use smaller tubing like for racking and just put that into the stopper. You guys do this? Any problems with clogging or the stopper popping out?

Thats exactly what I do, I bought a longer hose for my racking cane and cut a couple feet off of it for a blow off. I put it directly in the stopper like I would an airlock and haven't had a problem yet.

Cool. Thanks.