MLB star Aroldis Chapman is apparently quite the mama's boy ... 'cause the Pittsburgh Pirates pitcher shared a bizarre video of himself grabbing an older lady's boobs this week -- and many believe it is his very own mother.
The two-time World Series champion posted the disturbing clip to his Instagram story ... showing him cozying up on a couch with a woman who resembles his mom, Maria Caridad De La Cruz.
Chapman -- who's grinning from ear-to-ear -- is super handsy throughout the vid ... squeezing both boobs as the woman pats his back.