Toys play a crucial role in the mental stimulation of pet rabbits by providing them with opportunities for exercise, exploration, and enrichment. Toys keep rabbits engaged, prevent boredom, and help them exhibit natural behaviors such as chewing, digging, and foraging. Interactive toys like puzzle feeders can also challenge their problem-solving skills, keeping their minds sharp and engaged. Overall, toys are essential for promoting physical and mental well-being in pet rabbits.