Phillies fans made sure Justin Verlander got anything but a warm welcome when he showed up to the stadium for Game 3 of the World Series ... and the ace returned the favor by flipping them off!!
The playful moment went down when the Houston Astros' team bus made its way to Citizens Bank Park for Monday night's matchup ... and when it passed by a group of Philadelphia backers, JV decided to give the finger.
The fans loved it ... with one person even saying, "That was great!