Paul "Lab Rat" Squirfenherder is the Grossology Department's tech support, designing and building gadgets and vehicles to aid Grossologists on their missions, and is also a friend of them. He likes to work hard, spending most of time doing lab experiments that it earned him the nickname “Lab Rat”. His quite impressive inventory of hi-tech gadgets and various scientific knowledge make him valuable to the team. He has a pet rat named Hermes, who he treats as his best friend. He is very closed to his pet and is seems to be very affective with animals. Lab Rat suffers from Agoraphobia, and he only ventures out of the Gag Lab for Hermes’ well being. He has lacks in social skills and then sometimes acts or sounds stupid. Also he has a poor personal hygiene, Abby often jokes that he stinks due to the fact that bathing is not one of his favorite activities. The episode "Owl Most Foul" shows Lab Rat not only stepping out of the Gag Lab for the first time, but also wearing his blue slime suit for the first time. Lab Rat joined the Bureau of Grossology after being caught by the authorities (police) when he was on a slime spree, as he was a prankster. He was sent to juvenile hall and joined the Bureau as an alternative to being put in juvenile prison. He also made two robots. One is a robot version of Hermes and the other one is a robot dog called Sniffer Mac Gross. Lab Rat also has a severe mango allergy.