From dailymail.co.uk:

Ralphie: “Dolphins getting high? That does it, if next they develop karaoke for themselves, they can run for president!”

What does a dolphin use to get high? A toxic puffer fish that makes them lapse into a trance-like state

• The footage features in TV series Dolphins: Spy in the Pod
• Series uses several cameras disguised as sea creatures to film dolphins
• The mammals were filmed in a trance-like state after eating puffer fish

In an extraordinary scene filmed for a new TV series, the dolphins are shown gently passing the fish between them. Experts believe the creatures are using the toxins, which emerge from the puffer fish as part of its defence mechanism, for their own enjoyment.

At one point the dolphins are seen floating just underneath the water’s surface, apparently mesmerised by their own reflections.