They were so heavily laden with their ill-gotten gains they had to bury the treasure before making their escape.
8 seconds sound clip from the Garfield's Halloween Adventure (1985) movie soundboard.
You can hear this line at 00:17:28.705 in the Blu-ray version of the movie.
Quote context
[...]
- What I am about to tell you has never been told to another living soul.
- This island has a secret. A deep, dark secret it has held for 100 years.
- One hundred years ago, tonight, a ruthless band of pirates held up in this very house.
- They had looted many ships and were pursued by government troops.
- However, before they left this island on that stormy night, they signed a contract written in blood.
- The pirates had a 10-year-old cabin boy. I was that boy. I was there.
- I never took the treasure because they would have found me.
[...]