tum

The “rooty toot toot” is simply the noise the horns make, while “rummy tum tum” is the drums.

So Virgil, "Solemnes tum forte dapes et tristia dona ante urbem in luco," &c.

Mappo, who had been watching Tum Tum learn to stand on his hind legs, now looked at the man and dog.

Mappo was indeed getting homesick for the jungle, and for his folks, but when he saw Tum Tum, he felt much better.