She said it happened on a whim, inspired by a newspaper article with the headline: “Boomers believe they’ve found a fountain of youth in a syringe.’’ She said it happened in her posh master bathroom.

She said she pulled up her shirt so that Brian McNamee could pinch her skin and inject her with human growth hormone in the belly. She said no one else was there.

“I don’t think [her husband] thought it was bad,’’ she testified. “It wasn’t like doing heroin or something crazy.’’

Debbie Clemens was always going to be a risky witness for her husband, and that was the case Friday as the perjury trial of the former pitcher reached the end of its eighth week. The defense is expected to rest Monday, and the jury could perhaps begin deliberations Tuesday afternoon.

Roger Clemens is charged with lying to Congress in 2008 when he denied using steroids and HGH. He’s also charged with obstructing Congress by telling 13 alleged untruths. Among them: Roger Clemens’s claim that his wife’s injection occurred without his prior knowledge or approval, and his claim that he wasn’t at Toronto Blue Jays teammate Jose Canseco’s Florida house on or about June 9, 1998.

Debbie Clemens contradicted that second statement outright: She said the Clemens family - Roger, Debbie, four sons, Debbie’s brother and a nanny - spent the night at Canseco’s house during the June 8-10 series of games against the Florida Marlins but they were not at the pool party as McNamee claims.

McNamee had testified he injected Roger Clemens with performance enhancing drugs. While McNamee and Debbie Clemens gave differing accounts, her testimony might have bolstered McNamee’s credibility: The jurors now know he was telling the truth when he said he gave her an HGH shot during one of his extended stays at the Clemens’s home in Houston.

McNamee said Roger Clemens was present for the shot his wife received.

The obvious question: Why did she let McNamee do this to her - in such an intimate setting - without consulting a doctor or her husband?

“I was totally comfortable,’’ she said. “I didn’t know there was anything bad about it.’’