* Catch a tiger by your toe, if he hollers let him go, ene meani mini mo.
* this little piggy went to market, this little piggy stayed home, this little piggy went to market, this little piggy stayed home, and this little piggy goes wee, wee, wee all the way home.
* there was a farmer who had a dog and Bingo was his name-o, B (clap) I (clap) N (clap) G (clap) O (clap)
Or when he reads books, how he makes up story lines that fit inline with the story I've read to him a gazillion times. Goodnight Gorilla, Snuggle Puppy or Moo, Baa, La, La, La which at the end has a part to ask the child "what do you say?" Last night J popped off with "The End!" He was so proud of his response, he preened like a peacock.