Definitely non compos mentis. Better summon the authorities.
4 seconds sound clip from the Daffy Duck's Quackbusters movie soundboard.
You can hear this line at 01:06:15.651 in the DVD version of the movie.
Quote context
[...]
- Daffy Duck, ace paranormalist, at your service.
- Hello? Hello, Mr. Duck? I wanna report an elephant in my birdbath.
- I beg your pardon, sir. You say there's an elephant in your birdbath?
- Definitely non compos mentis. Better summon the authorities.
- No, no. You wait right there, sir. Somebody will be coming to call on you very shortly.
- Now what was that address again?
- Yeah, that's right. Please, hurry.
- Steady, now, lad. Easy does it.
- But I did. I did see an elephant in my birdbath.
- Sure, sure, I know. I keep a giraffe in mine.
[...]