It's The Riddler. His modus operandi alright.

4 seconds sound clip from Batman (1966) - A Riddle a Day Keeps the Riddler Away (S1E11) TV Series.

You can hear this line at 00:05:34 in the Blu-ray version of the movie.

Quote context

[...]

- What do you mean, Aunt Harriet?

- Well, it's just that every once in awhile you come zooming out of this room like jet planes, practically knocking me over and then rushing out with hardly any explanation.

- There's no mystery. Dick and I just played a game of chess and we agreed that if I won, he'd do some studying. If he won, we'd go fishing. Bye, dear.

- Batman, I'm having trouble... With a riddle.

- Him again.

- We'll be right over. To the Batpoles.

- It's The Riddler. His modus operandi alright.

- I agree. Nobody else would use such a spectacular and bizarre method to flaunt a puzzle.

- What the devil is the culprit trying to tell us?

- The riddle itself is pretty basic. A person is a piece of wood when he's a ruler.

- You figure it has something to do with King Boris?

- Maybe.

[...]