One word.
2 seconds sound clip from the Daffy Duck's Quackbusters movie soundboard.
You can hear this line at 00:33:42.596 in the DVD version of the movie.
Quote context
[...]
- Help! Save me! Ahh! Ahh! Save me! He's a killer! Help!
- Most outrageous exhibition of wanton cowardice.
- Sylvester, now, where have you been?
- He's a complete basket case.
- Monster!
- Why, that's just a little old canary bird fluttering in the breeze.
- You yellow dog of a cowardly Sylvester, you.
[...]