A chameleon can shift from blue to green to black, and that sounds impressive at first. But the joke lands in the second couplet: no matter what color he takes on, he is still just a small chameleon. The drawn-out “cham-e-le-on” gives the ending a gentle, amused shrug.
The speaker isn’t awed or solemn; he sounds tickled and matter-of-fact. The mood is light and almost teasing, like a nursery rhyme with a pointed observation tucked inside. Read as more than a joke, the lines suggest that changing your surface or adapting to your surroundings doesn’t change who you essentially are. The chameleon’s “knack” is useful, but it has limits—his size and nature remain the same. That keeps the poem funny and a little philosophical at once, without ever becoming heavy.