My Dog Digs Holes. A LOT.

And if you can give me advice on how to stop him that would be just dandy.
I feel bad for him, he's just bored and hot. And BELIEVE ME, he knows he's not supposed to do it. When we get home, he looks at us all weird (as if guilty). And everytime that guilty look is on his face, we find a hole. People say its impossible to break it, but I don't wanna just say
"No bad boy" if he already knows he's not supposed to do it...you know?
So maybe you guys know stuff about dogs digging holes XD
Because I've lost all hope, and yes, have turned to Mibba.