My house has been playing A LOT of this lately and it made me curious, what's your favorite way to take someone out? 
 
Personally, I love jackhammering someone through the bottom of the stage into the water. Yeah, you die too most of the time but it's still worth it.

The good old baseball bat with its awesomely satisfying *smack* sound and home-run jingle will always be a favourite of mine.

Most satisfying is a Super Sheep from somewhere super crazy.
 
Best kill is a whole team with the Concrete Donkey though.

Prod. 
 
Just give 'em a little push...into the dark, deep blue.

The Holy Hand grenade never gets old

Using a banana bomb on a group of enemy worms. Very satisfying.

I guess it would have come up already but is there a low gravity pick up in this game like the Armageddon for ps1? I loved the baseball bat combined with this. Ultimate overkill.  
I find a domino effect really satisfying though- chaining up about three guys whose tombstone explosions each kills the next one.