Here's the deal -- prior to the massive blockbuster's release, Ryan Reynolds said there was just one joke the Mouse House asked to be removed ... but he didn't want to say what it was at the time.

Thanks to Disney submitting the script for awards contention ... fans now know what the joke was ... "F***! What we can’t even afford one more X-Man? Disney is so cheap. I can barely breathe with all this Mickey Mouse cock in my throat.”

A source close to RR tells TMZ ... it was Disney head honcho Bob Iger who asked -- but did not demand -- that the joke be cut.

We hear Ryan was totally cool with the ask since it was just a one-off and had nothing to do with the story. After all ... Disney clearly let him and his team get away with anything else they wanted in the R-rated flick full of F-bombs and bloody action.

Director Shawn Levy also noted before the film's release that a single line was cut at the behest of Disney ... but he swore he nor Ryan would ever say what was cut.