This page of the guide to Disco Elysium contains a detailed walkthrough of the Open trash container quest.
In the Open trash container quest in Disco Elysium you need to open a locked dumpster which is located behind the Whirling-In-Rags hotel. This can be done in two ways.
Getting the key is the easiest way to open the container behind the Whirling-In-Rags building. Enter the hotel and ask Lawrence Garte for the key - you will get it without any questions.
Use of force
The second way is a little more complicated, because you need to use the Prybar and also pass the legendary Physical Instrument check, which may fail if your character isn't physically prepared for it.
In the container you will find old clothes of the hanged man and two other items:
- Denim jeans: starts the Who put the clothes in the trash? quest;
- Olive-drab military overgarment;
- Damaged Ledger: completes a secret side quest Find your paperwork;
- Yellow-Man Mug: once you find this item, you'll be able to later press Gary, whom you can interview about the clothes thrown in the trash.