Final answer:
Billy has most likely taken a hallucinogen, which is a class of drugs that cause profound alterations in sensory and perceptual experiences. These drugs temporarily disrupt communication between neurotransmitter systems in the brain and spinal cord.
Step-by-step explanation:
Billy has most likely taken a hallucinogen. Hallucinogens are a class of drugs that cause profound alterations in sensory and perceptual experiences, often with vivid hallucinations. These drugs can be found in some plants and mushrooms or can be man-made. They work by temporarily disrupting communication between neurotransmitter systems in the brain and spinal cord that regulate mood, sensory perception, sleep, and other functions.