Dolphins have a reputation for being happy friendly animals, partly due to their incredible intelligence and Flipper-like portrayal in the media. We’ve already exposed that dolphins are capable of being gigantic jerks and have even been witnessed using a dead fish as a masturbatory tool (highly NSFW video), but now it appears that these underwater deviants also get high recreationally from a potentially lethal source.

Emmy award-winning filmmaker John Downer was filming the upcoming two-part miniseries Dolphins: Spy in the Pod when he noticed that bottlenose dolphins would gently chew on a pufferfish and then pass it to another dolphin in the pod. He noticed that after chewing on the pufferfish, the dolphins would look very tranquil and dazed. Then it hit him: these dolphins were getting high on the nerve toxin released by the pufferfish.

If his prior knowledge of pufferfish toxin wasn’t an indication of what these dolphins were doing, their subsequent behavior was a dead giveaway. They spent a great deal of time observing their own reflection on the water’s surface and acting very strange in general.

Downer’s crew was able to get this inside look through creative spy cameras, similar to what has been used for many of his other documentary miniseries. Underwater shots were taken with fish-shaped cameras while above water shots were taken with a camera that looks like a inconspicuous sea turtle. With the dolphins surrounded by cameras that looked like normal, everyday sea creatures, they were more relaxed and exhibited behavior that may not have been captured with traditional filming techniques.

Episode 1 of Dolphins: Spy in the Pod will premiere Thursday on BBC One at 8:00 pm UTC. The dolphins getting high on pufferfish toxin will be shown on Episode 2, which will air on January 9.