And here it is.
The five little monkeys....
... and the crocodile.
There are several versions out there (and when I originally did this one, I had the crocodile burp out the monkeys, but now I just go for it with the snapping and the chomping), but this is the one I use:
Five little monkeys swinging in a tree
Teasing Mr. Crocodile "you can't catch me!"
Along comes Mr. Crocodile, quiet as can be
And he SNAPPED that monkey right out of that tree!
Keep going till you have no monkeys left. I always ask the kids how many monkeys we have after each verse and when we have no more (they either say zero or I supply the word when they say "none!" - yay vocabulary building), I say "well then I guess we'll have to do something else!" And we do.
I've occasionally used the monkeys without the crocodile to do the monkeys on the bed rhyme, but I find it far less fun. This is also a great transition rhyme between Caps for Sale (it has monkeys) and Snip Snap, What's That? (it has a crocodile).