He always drank from his favorite mug, Sam. This looks like a piece from that mug. I don't know how it got broke.
7 seconds sound clip from the Garfield's Babes and Bullets (1989) movie soundboard.
You can hear this line at 00:18:32.366 in the Blu-ray version of the movie.
Quote context
[...]
- You loved him. He didn't love you. So you snuffed him.
- Yes! Yes, I loved him. He didn't love me. I couldn't have him. So I...
- The tears were streaming down her face and falling like rain off a pine tree.
- But the coffee stains, the painted piece of ceramic cup.
- Kitty, did you have any duties in the office other than making coffee?
- Wait a minute. Filled his prescriptions?
[...]