Tommy Pham grew so frustrated with a fan during the Pirates' tilt vs. the Angels Wednesday, he busted out an obscene gesture toward the person ... and it's all probably going to result in a stiff fine.
The Pittsburgh left fielder's spat with a Halos supporter began during the fifth inning of the Buccos' matchup with L.A. at Angel Stadium ... when a man clad in red leaned over some railing and touched Pham while he was digging for a ball in left field.
The Pittsburgh star clearly didn't appreciate the physical interaction .