Highly Suspect Puns

My dad is a police officer and I was on a ride-along with him. He and his partner arrested a guy for shoplifting. As the perp, whose name is "Unique," is sitting in the back of the car, my dad walks up, looks at me smiling, and says to the suspect "how do you catch a unique criminal? Unique up on em!" He and his partner laughed and high-fived, then just shut the door.