Isn't it obvious? Sit? ... Sit??? ... Sit???!!! When I put on 140 pounds of canine muscle, I'll be telling you to sit, MOFO!
As a former beagle owner (the kids wanted a dog "just like Snoopy"), I have to say that's my worst nightmare. My beagle, Casey, had a bad habit (one of many) of digging under the fence and roaming the neighborhood. He met an untimely end involving an SUV.
We own a beagle too and can't imagine a better dog. I was warned that a beagle would howl and dig but then someone else said that was only if neglected. Our dog gets plenty of love and attention and got plenty of discipline early so now he's a very obedient and fun dog.