Vanessa Bell Calloway Says 'What's Love Got To Do With It' Slap Was Real

Vanessa Bell Calloway has been turning in impeccable performances for more than 3 decades -- but in "What's Love Got to Do With It," she wasn't acting at all ... at least in the film's most iconic scene.

Fans will remember the 1993 biopic follows the meteoric rise of Tina Turner -- played by Angela Bassett -- and her then-husband Ike -- played by Laurence Fishburne.

Vanessa plays Tina's fictional friend Jackie in the movie, who gets slapped by Ike when she sticks up for Tina in a diner.

Now ... the textbook way to film a slap scene is for the slap-ee to move their head violently out of the way before the slapper can actually make contact -- then the sound is added in later. But apparently, that is not what happened.

In an interview with Cocoa Butter, Vanessa explained she and Laurence rehearsed the correct way to stage the slap, and they were going great ... until one take they missed.

Vanessa explained, "We didn't have the eye connection, and he slapped the living s**t out of me and my face was pounding."

And anybody who remembers the scene knows ... she's not lying. It's right there on film -- Jackie does a full somersault as a result of the epic blow absorbed from Ike.

She continued ... "One side of my brain was like, 'Ow!!!' The other side was, 'Keep going, Vanessa! This is gonna be good.'"

She did keep going ... despite everyone around frozen by the fact that they know they just heard a real slap.

"And that's the take they used," Vanessa revealed.