Come on, how ‘bout a big hippo-hippo-hooray for Jada?

How did petite Jada Pinkett Smith turn herself into a hippopotamus?

By agreeing to co-star in a new DreamWorks animated film.

She puts her voice to Gloria the hippo, one of the four star animals of “Madagascar,” which opened Friday.

“You’d have to ask the directors how they thought of me,” Pinkett Smith says. “But I just thought it’d be cute to have my voice come out of a full-figured gal.”

In fact, she says, she tried to keep her voice in a higher register, just to underscore the contrast.

“Gloria is a big hippo who is strong and tough, so you might think we would need to get somebody big for the role, but Jada is one of the strongest, toughest women I’ve ever met,” says co-director Eric Darnell.

“She will not be pushed around and knows what she wants in life, and that’s exactly who Gloria is.”

(For a more conventional example of Pinkett Smith’s strength in a role, check out her performance opposite Tom Cruise and Jamie Foxx in last year’s Oscar-nominated “Collateral.”)

Pinkett Smith says Jeffrey Katzenberg, a founding partner of DreamWorks who oversees the animation division, approached her for the “Madagascar” role.

“And I trusted Jeffrey, who assured me it would be a great project,” she says.

Now Pinkett Smith says she’s also glad she took the role because she and her husband, actor Will Smith, have two young children who can enjoy the film.

“They were so surprised and excited to hear Mommy’s voice come out of the hippo,” she says.

In “Madagascar,” Gloria is a bit of a mom to three rather juvenile male animals: Alex the lion (voiced by Ben Stiller), Marty the zebra (Chris Rock) and Melman, a very neurotic giraffe (David Schwimmer).

“(Gloria) looks after the boys and tries to keep them out of trouble,” Pinkett Smith says of her character.

Now 33, Pinkett Smith, who got her start in “The Cosby Show” spin-off “A Different World,” is becoming a renaissance entertainer.

She’s acting in films, writing and producing television shows, authoring a New York Times best-seller called “Girls Hold Up This World,” (Cartwheel, $16.95), and co-hosting (with her husband) the BET Awards telecast on June 28.

She’s also the lead singer of Wicked Wisdom, a band scheduled to tour with heavy metal rockers this summer as part of Ozzfest.

As if motherhood weren’t enough, Pinkett Smith says she needs such diversity to keep herself busy, adding that good movie roles just aren’t plentiful enough.

“Unfortunately, it’s hard for us chicks in Hollywood now,” she says. “I have possible films in development, but I’m working more now on TV and music.”

The birthday bunch

Actor Clint Walker (“Cheyenne”) is 78. Actor Keir Dullea (“2001: A Space Odyssey”) is 69. Actor Michael J. Pollard is 66. Actor Colm Meaney (“Star Trek: The Next Generation”) is 52. Actor Ted McGinley (“Hope & Faith”) is 47. Actor Ralph Carter (“Good Times”) is 44. Country singer Wynonna is 41. Guitarist Tom Morello (Audioslave, Rage Against the Machine) is 41. Rapper Cee-Lo (Goodie Mob) is 31.