Since v0.4, players can deal drugs to a new batch of customers. The park offers a new drug dealing opportunity that will allow you to sell items to the trio, a bunch of 18-year-olds skipping school.
To begin, you'll need either 20 Notoriety or the 'Thug Life' tattoo. This will allow you to meet the trio. Once you've met them, you'll need to convince them you're not a narc. This can be done by the following methods:
If you don't have any of the following when you initially meet the trio, don't worry. You'll be able to come back at any time.
Once they have your trust, you can sell them the following. Make sure you have ample supply, as initiating drug dealing costs 1 energy.

Park drug dealing is less lucrative than doing so at the truck stop, but it is also less risky. You can also acquire some of the items for free during various events. Much like truck stop drug dealing, if your Stress or Notoriety gets too hard (90 for Stress, 100 for Notoriety, opposite from the truck stop because I'm quirky like that), you'll have to leave.