This is what I love about the Lonely Island Boys.
They take an idea like this, which has been done before, and they add the extra bit of awesomeness to it.
I think this idea goes much further than the regular sight gag. Though Andy's physical comedy is still pretty simple you can tell he is getting better every day. And Zombies for no reason? You can tell the Lonely Island Boys are with the new generation. Though it seemed tacked on it works because the viewer probably thought that the skit was going to end on the "Murder" gag.
These guys need their own skit comedy show on ABC to replace that Cavemen show which predictably isn't going anywhere.