We got Sam at Bristol Farms in L.A. Tuesday, who certainly didn't pull any punches on the heels of a new Britney documentary that rips Jamie and the conservatorship -- Sam also teed off Tuesday morning on IG, saying he has "zero respect" for Brit's dad.
Britney's BF accuses her pops of trying to control their relationship and claims Jamie constantly throws obstacles in their way. Although he says he won't go into details, you can tell Sam has a lot more to say ... and now says he's not afraid to speak up.
Sam's outburst comes as 'Framing Britney Spears' is getting a lot of attention. The Hulu doc has fans fired up about how the pop star's been treated over the years by Jamie and others.
We normally don't hear much from Sam, so this is a pretty big mic drop.