This has gotta sting!!
Alex Rodriguez was just trying to talk some baseball during American League Championship Series coverage on Monday ... when Boston fans used it as an opportunity to ruthlessly troll the hell out of him about Jennifer Lopez and Ben Affleck.
A-Rod -- who's doing analysis for Fox's coverage of the postseason -- was hit with verbal jabs before and after the Red Sox beat the Astros ... with fans in the crowd chanting 'J Lo' and 'Aff-leck' and even more harsh phrases like, "She left you with Ben Affleck!