SANTA MARIA, Calif. – An ex-maid for Michael Jackson testified yesterday she caught the star showering naked with a cute young boy who grew up to become Britney Spears’ choreographer.

Blanca Francia, who worked for Jackson from 1986 to 1991, also said that besides Wade Robson, Jackson’s bedmates included then child star Macaulay Culkin and a diaper-wearing chimp named Bubbles – who bit her twice.

Francia said she became “uncomfortable” with Jackson’s relationships with kids the day she found him showering with Robson, whose tiny “green-neon color” underwear were on the bathroom floor next to Jackson’s white cotton briefs.

“I heard laughing and playing around … I walked [in] and they were in the shower. Mr. Jackson was taking a shower with little Wade,” said Francia.

Francia said she could see the “figure” of Jackson and of “the little kid” through the “cloudy” haze of steam on the glass shower door, but she couldn’t see if they were touching or what they were doing.

“I hear two people playing. … I was gonna talk to them, but I left,” she said, fearing that Jackson “was gonna get mad.”

The incident happened in 1989 or 1990 when Robson was about 8, she said.

Robson and Culkin have repeatedly denied ever being molested by Jackson. Both are expected to testify for the defense, if called, sources said.

In 1993, after a different 13-year-old boy accused Jackson of sexual abuse, Francia’s own son alleged he, too, had been molested between 1987 and 1990.

Jackson paid the mother-son team a $2 million-plus settlement to keep them quiet.

On cross-exam, defense lawyer Tom Mesereau went on the attack, telling the jury Francia rifled through another employee’s purse, had her wages garnished by creditors and was caught with a phony Social Security number. It was also revealed that she signed a $20,000 deal in 1993 to talk to the tabloid TV show “Hard Copy.”

Jurors listened closely to the details offered by the pop star’s ex-personal maid, who worked for him at three different homes – the Encino, Calif., mansion where Jackson’s parents now live, an L.A. high-rise apartment called “The Hideout” and Neverland Ranch.

She cleaned his bedrooms and bathrooms, changed his linens, did his laundry, helped him pack for trips and delivered him snacks, like popcorn. She had the key to his private chambers and could enter at will after knocking, she said.

In sharp contrast to several recent ex-Neverland employees, who portrayed Jackson as a frequent boozer, Francia didn’t say a word about Jackson drinking or even asking for alcohol.

She said Robson was a frequent visitor to Neverland around 1989 and 1990 but stopped visiting at some point and was replaced by Culkin.

Most of the time, the “Home Alone” star came with his parents and several siblings, she said. But “maybe about two times” Culkin visited Neverland alone, and apparently slept in Jackson’s own bed, she testified.

“Was there a separate sleeping arrangement when Macaulay Culkin was there?” prosecutor Ron Zonen asked.

“No,” she replied.

Culkin’s father, Kit, told the Daily News on Sunday that his son never slept with Jackson.