Calvin Harris: Taylor Meeting Tom's Mom Is a Joke ... Just Ask MY Mom

Calvin Harris thinks it's "f****** laughable" that Taylor Swift has already met Tom Hiddleston's mother ... considering she NEVER met Calvin's parents during their 15-month relationship.

Sources close to the former couple tell TMZ ... Calvin wanted Taylor to meet his parents, who live in the U.K., but Taylor always told him it was too far away.

We're told Calvin was understandably "bewildered and astonished" when he heard about TayTom's visit to meet his mother, Diana ... in the freakin' U.K.!! Remember, Hiddleston's only been in the picture for a few weeks at this point.

What's the rush? One source says Calvin thinks Taylor's cozying up to Tom to lock down a Bond girl role ... IF he becomes the new James Bond, as rumored.

If it sounds like sour grapes, it's not -- we're told it's more comical to Calvin, who also feels like he dodged a bullet.