Prom night rears its ugly, or at least its hairy, head on the latest episode of “My Gym Partner’s A Monkey” (6 p.m. and 8 p.m., Cartoon Network). For the uninitiated, this cartoon follows the hijinks of a human boy assigned to a junior high school filled with zoo creatures. Due to a typographical mix-up, young Adam Lyon is confused with a real lion and assigned to the Charles Darwin Middle School. There he must share classes and lockers with chimps, elephants, giraffes, goldfish, a myopic armadillo and even some kind of bug.

If adjusting to the jungles of junior high weren’t difficult enough, Adam must find a date for the big dance. He has developed a crush on a girl at his bus stop and wants to ask her, but his best friend, a needy and manipulative monkey, convinces him that no human dates are allowed. Things are complicated further when a gangly adolescent giraffe named Audrey sets her romantic sights on Adam. It’s not giving too much away to reveal that boys of a certain age are lower primates at heart, and that girls of all species just want to have fun.

¢ Speaking of animals, the National Geographic Channel offers a three-hour marathon of “The Dog Whisperer” (7 p.m., National Geographic). Host Cesar Millan and his show have become pop icons in a short period of time.

Like a lot of addictive cable TV shows, “The Dog Whisperer” repeats itself into a well-worn groove. In nearly every “Whisperer,” Millan must use snippets of psychology and New Age inspiration to convince a delusional human to stop treating the dog like a child or a friend and start acting like the pack leader that the dog can respect and obey.

Despite its simple message, “The Dog Whisperer” lore only grows. Within the past few months, Millan has published a book of advice, “Cesar’s Way: The Natural, Everyday Guide to Understanding and Correcting Common Dog Problems.”

He’s also appeared, as himself, on an episode of “South Park.” Unlike Chef, his two-dimensional character survived the experience without being dismembered or humiliated. He actually “trained” Cartman to behave like a kind and considerate child. The rotund cartoon monster resorted to form only when his mother resumed her bad habits, spoiling him and treating him like he was her “best friend.”

Tonight’s other highlights

¢ “Sexiest Southern Women” (7 p.m., CMT) counts down the top 20 belles. Followed by “Sexiest Southern Men” (8 p.m.).

¢ Julia Roberts and Kirsten Dunst star in the 2003 period piece “Mona Lisa Smile” (7 p.m., Fox).

¢ The murder of a surgeon’s wife leaves few clues on “Close to Home” (8 p.m., CBS).

¢ Tom Selleck portrays Gen. Dwight D. Eisenhower in the 2004 cable film “Ike: Countdown to D-Day” (8 p.m., A&E).

¢ A bitter former employee of a drug firm appears to be tampering with the product on “Numb3rs” (9 p.m., CBS).