I'm desperately trying to make the second joke funny (because it isn't.) Could you have misquoted it? Could it be: Two lambs are playing soccer. One lamb kicks the ball and makes a goal. The other lamb says "You won." The first lamb answers "You too!"

I don't "get" the second joke, sorry. In the first joke, there are two parts. The first part of the joke seems annoying. You can't guess the answer, because it's not true. Ducks don't have webbed feet in order to stamp out fires. The riddle can't be guessed because it doesn't make any kind of sense. Obviously a duck cannot put out a fire that way, and would get burned in the process. When we hear the second part of the joke, we have stopped thinking, because logic didn't work on the first part. We're just going to say "I don't know, why?" just to get it over with. The second part of the joke then surprises us because it does have a crazy logic to it, and we suddenly understand the "point" of the first part. It was a setup for the second part.

They are funny because they are bad

Elephants are known for putting out fires. This is kind of a dumb joke. I believe the punchline of the second joke is a play on words, called a pun. The lambs are calling each other ewes, an animal that is in the same family. A "ewe" sounds like the word you. They have the same sound but different meaning, although, ultimately even doing that doesn't really make it that funny. It would be the same to make a joke about goats, saying "no kidding" to each other. No kidding means don't joke with me. a kid is a baby goat. Does that make sense?