The lambs do several things well. The eat a lot, pee and poop a lot, and they play "smack the cranium" a lot. As they have gotten bigger, the sound of their hooves thundering across the grass, followed by the CRACK of their skulls colliding is a bit... thunderous.
Having been on the receiving end of a few gentle butts from the boys, I am very respectful of their strength. The dogs are, too. We are beginning to walk softly and carry a big stick when we are in the yard with "the boys."