A mere ruse, commissioner. A clever device to make you call me in.

6 seconds sound clip from Batman (1966) - Hi Diddle Riddle (S1E1) TV Series.

You can hear this line at 00:06:28 in the Blu-ray version of the movie.

Quote context

[...]

- Right, commissioner. There's a problem.

- We all know how this quizzical criminal operates. He deliberately leaves clues to confound us.

- Clues which may or may not lead to the real crime he's planning.

- The real crime?

- Precisely, Inspector Basch.

- The Riddler contrives his plots like artichokes. You have to strip off spiny leaves to reach the heart.

- But surely, Batman, there must be some sort of political plot against Moldavia. That exploding cake...

- A mere ruse, commissioner. A clever device to make you call me in.

- But why? Why would he want that? You're his deadly nemesis.

- The Riddler's mind is twisted. Crime's no fun for him unless it means outwitting us.

- Robin's right.

- He has this strange, artistic compulsion to... Artistic. That's it. The meaning of the first clue.

[...]