1 Lambert: {still in darkness} Riddle contest, eh? Okay then... What's green, has six legs, and will kill you if it drops on you from a tree?
2 Gollum: Too easy, it iss! A billiardss table! How did the man drown in his muessli?
3 Lambert: Erm... He got pulled under by a currant! How do you know when there's five elephants in your refrigerator?
4 Gollum: There'ss a Volkssswagen parked outside!
4 Lambert: Dang, you're good.

I knew I'd find an excuse to use some of my favourite silly riddles one day.

The last one is a good example of a joke that you can only understand if you have prior knowledge. (i.e. a serial joke, as opposed to the second one, which is a cereal joke.) I suspect most readers will get it, but there'll probably be a few who don't, so I offer the following:

How do you fit five elephants in a Volkswagen?

Two in the front and three in the back!

How do you know when there's an elephant in your refrigerator?

There's footprints in the butter!

How do you know when there's two elephants in your refrigerator?

There's two sets of footprints in the butter!

Okay, now go back and re-read the comic. :-)