getting-high
Explanation
The Joke
A parent walks in on their child Bobby and asks, "Bobby! Are you getting high in here?" Bobby responds with the classic deflection: "The only thing I am high on is life." The final panel reveals the punchline -- Bobby is holding a psychedelic mushroom (likely an Amanita muscaria, recognizable by its red cap with white spots) and has a small lizard or toad nearby, as he clarifies: "Specifically, kingdoms Animalia and Fungi."
Bobby is technically telling the truth: he IS high on "life" -- specifically, on living organisms from the biological kingdoms Animalia (animals, presumably licking or handling toads that produce psychoactive compounds) and Fungi (psychoactive mushrooms). The joke transforms the wholesome anti-drug slogan into a literal biological classification of his drug sources.
The Humor
The comic takes the well-known anti-drug catchphrase "I am high on life" and subverts it through biological taxonomy. The humor lies in the double meaning: "life" in the colloquial sense means existence and its joys, but "life" in the biological sense encompasses all living organisms -- including the ones that produce psychoactive substances. Bobby has found a technically truthful way to admit to drug use while sounding like he is delivering an after-school special. The visual details -- the toad (likely a Bufo toad, which secretes psychoactive compounds) and the red-capped mushroom -- reinforce the joke perfectly.
References
The biological classification system referenced here is Linnaean taxonomy. Kingdom Animalia includes all animals, and Kingdom Fungi includes mushrooms, yeasts, and molds. The Amanita muscaria mushroom (fly agaric) with its distinctive red cap and white spots has a long history of psychoactive use. Certain toad species, particularly Bufo alvarius (the Colorado River toad), secrete 5-MeO-DMT, a potent psychedelic compound.