A third accuser took the witness stand – at Bill Cosby’s sexual-assault retrial in suburban Philadelphia.

Janice Baker-Kinney was a 24-year-old bartender in 1982.

That’s when she says Cosby gave her two pills that made her lose consciousness. She testified Wednesday that she woke up naked in bed with the comedian – believing they’d had sex.

Baker-Kinney says she believes Cosby gave her Quaaludes, a now-banned sedative ..but she says she still blames herself for getting knocked out – telling jurors, “I don’t want to have that guilt and shame.”

Cosby is charged with drugging and assaulting a woman at his home in 2004 – but he says it was consensual.

Prosecutors are calling other accusers to the stand – to make the case that Cosby is a serial predator.

Cosby’s lawyers have said Baker-Kinney “voluntarily” took the drug – and apologized to the comedian for passing out.