Deadpool is known as the Merc With a Mouth, but according to screenwriters Rhett Reese and Paul Wernick, that mouth actually took a lot of work to develop. Deadpool's sense of humor is dark and pervasive, and some of the film's best lines apparently had many alternate versions.
“All night long during the shoot, we were running in and whispering names in Ryan’s ear,” Reese told Entertainment Weekly of the scene when Deadpool calls Gina Carano’s Angel a “less angry Rosie O’Donnell."
“My preferred choice was Criss Angel, Mindfreak.” Other options included Kevin Sorbo, former WWE wrestler Chyna, Jose Canseco, “Louise Ferrigno,” and Busta Rhymes.
“God Bless Gina Carano for being such a good sport,” Reese said, explaining that she took some of the jokes to heart. “Chyna, the professional wrestler, was one of the names, and Gina, with her background in MMA fighting, took that especially hard.”
But that wasn't the only joke that took some time to craft. Originally, Wade Wilson had bet on Alex Trebek to die in the "dead pool" game from which he later takes his codename. Wade would have said to Weasel, "A lot of people don't know this, but Alejandro's favorite color is cocaine."
“Implying that Alex Trebek is a cocaine addict and he’s likely to die of an overdose,” explained Wernick. “We though that was the most patently ridiculous rumor of all time. But it was so random that we worried if Trebek himself might find that unfunny. We also wanted to hit the story point that Weasel had bet on Deadpool. So discretion proved to be the better part of valor, and we dropped that one.”
One of the film's funniest scenes, in which Deadpool slowly threatens a thug with a zamboni, almost ended in a reference to another decidedly less successful comic book movie. As Deadpool closes in on the criminal, laying in a hockey rink, he was originally going to say "Ice to see you!" referencing Arnold Schwarzenegger's much-maligned portrayal of Mr. Freeze in Batman and Robin. Director Tim Miller eventually chose "You're going to die - in five minutes!" instead.
There are many more alternate lines and unseen gags detailed in the EW article right here .