That's a night when dogs have to help cats go out and get candy.
4 seconds sound clip from the Garfield's Halloween Adventure (1985) movie soundboard.
You can hear this line at 00:06:15.087 in the Blu-ray version of the movie.
Quote context
[...]
- He's ugly, too. It would take two of him to get any uglier.
- He's so ugly he wouldn't have to wear a mask to go trick-or-treating on Halloween.
- Garfield, you are a genius. I know that.
- That's a night when dogs have to help cats go out and get candy.
- That's right. And if a dog does a good job he gets a whole piece of candy of his very own.
- Well, do you wanna go, boy? Wanna go out and get candy? Do you? Do you wanna go?
- Okay. Let's go to the attic and find some costumes for tonight.
- You know, just between you and me, there are times when I love that dog.
- There should be some great Halloween costumes up here somewhere.
[...]