•Put Up With a Little Monkey Business: To impersonate the beast, Serkis wore a Lycra ape suit and gorilla dentures on the set (special effects make the 57" actor grow into a skyscraper-size simian). "I [was made fun of] day in and day out," says Serkis, 41, who did creature duty before as the hideous Gollum in Kong director Peter Jackson's The Lord of the Rings. "Everybody was chucking bananas, throwing peanuts, calling me monkey man."

•Be a Knucklehead: After spending more than a year running around on all fours, "my knuckles are absolutely trashed—they took a real beating," says Serkis, who lives in London with wife Lorraine Ashbourne and kids Ruby, 7, Sonny, 5, and Louis, 1. Still, he found the habit hard to shake. "I still catch myself making gorilla movements. When I lean forward, I always lean on my knuckles. It's really bizarre."

•Catch Jungle Fever: For homework, the former Shakespearean stage actor observed wild mountain gorillas in Rwanda. "The amazing thing was how different they all are," he says. "There's sibling rivalry, and teenage boys are always ready to scrap." What about Kong? "He's like a lonely, psychotic hobo who's past his prime. I wanted him to be as gorilla as possible but give him big emotional range."

•But Don't Ever Two-Time Your Primate: While studying apes at the London Zoo, Serkis got friendly with a female gorilla named Zaire. "I struck up a strong relationship," he says. "Then one day my wife came by, and Zaire didn't like it at all. She got a big water bottle and squirted my wife with it!"