Fernando Tatis Jr.'s first homer of 2023 didn't go as well as he would have liked ... he was booed as he rounded the bases -- and then the pitcher who served it up straight up called him a "cheater."
The San Diego Padres star hit the dinger on Wednesday night while down in the minor leagues as he continues to serve his 80-game ban for his positive PED test last season.
The 24-year-old, playing for the El Paso Chihauhaus against the Sacramento River Cats, smacked the baseball deep over the left field wall .