To keep a pet ferret entertained, you can provide them with a variety of toys such as tunnels, balls, and interactive puzzles. Additionally, you can let them explore different areas in your home (supervised, of course), set up a play area with boxes and tubes, and engage in interactive play with them using toys like feather teasers or fishing rod toys. It's also important to provide mental stimulation by hiding treats around their enclosure for them to find or rotating their toys regularly to keep things interesting.