==== SPOILERS ====
What I did:
- Get the scavenger skill (Checkpoint -> Scrapyard entrance)
- Scavenge in the 'Park scenic path' until you find location 'Muddy path'
- Scavenge in 'Muddy path' until you find accessory 'Bitch collar'
- Wear the bitch collar
- Go to park and meet the Wolfman
- Wear the bitch collar again
- Go to the park again (but you have to be willing, otherwise you will automatically reject entry)