Whether he was planning to hit somebody with the manhole cover, or use it as a shield, or what, I'm not sure. But he was involved in a scuffle before he went for the manhole cover--I've seen the clip with context before.

So he was going to brain someone with that manhole cover and fell in?!? Too funny!

It looked like it hurt, too!

It looks like an attempted murder by manhole cover.. good think he was too drunk to get anywhere with it.

Any time someone needs to do the "passing back and forth" bit, just take it for granted he is grabbing a new ubmrella. Just like the moving camera in that earlier clip about the "paper manhole cover".