Ex-49ers Brandon Jacobs RIPS Jim Harbaugh -- 'He's a B*tch'

Brandon Jacobs HATES his old 49ers coach Jim Harbaugh -- claiming the guy is nothing but a "bitch" who unfairly punished the running back during his short stint in San Fran.

Jacobs -- who won 2 Super Bowls with the Giants before spending 1 crappy season in SF -- just UNLEASHED on Harbaugh on the Boomer and Carton radio show:

"Going to the 49ers when I could have stayed in New York .. It didn't work out for me," Jacobs said.

"I wasn't liked ... I thought I was held hostage because of the previous year (when the Giants knocked the 49ers out of the playoffs).

"But, it is what it is. I got two rings and Harbaugh ... you know he's a bitch ... so it doesn't matter."