Phillies fans lived up to their ruthless reputation on Friday ... chanting "DUI" at Braves star outfielder Marcell Ozuna during Philadelphia's playoff game against Atlanta.
It all went down in the first inning at Citizens Bank Park in Philly -- Ozuna was up for his first at-bat of the afternoon ... when the fans trolled him over his August arrest.
"DUI! DUI! DUI!" the Philly faithful chanted in unison as 31-year-old Ozuna swung at an 81 MPH slider from Phillies' right-hander Aaron Nola.