A man goes to the zoo, for the day out.

He visits the lion's cage, but it's empty - not a lion to be seen.

So, he walks around a bit and ends up by the elephants. Not a nelly in the place.

Hmm, he thinks. I shall try the zebras. Every zoo has zebras. Nope, not one. Completely zebra-less.

Eventually, he finds one cage with one small, pathetic looking dog in it.

It's a shitzu.