Arnold Schwarzengger reveals how he tricked action star rival Sylvester Stallone to star in a horrible movie: 'Can you get more Machiavellian?'

In their 1980s and '90s heyday, action-star rivals Sylvester Stallone and Arnold Schwarzengger competed for nearly everything, including the best scripts, the best body, the biggest guns and the most kills per movie.

And in 1991, the Austrian-born 76-year-old even managed to trick the 77-year-old native New Yorker into starring in the critically reviled buddy cop action comedy Stop! Or My Mom Will Shoot, costarring Golden Girls scene stealer Estelle Getty.

Not only did Arnie get his agent to lie to Sly's agent about his desire to star in the 'fantastic' film, he even spoke with the director Roger Spottiswoode (whom he later worked with on The 6th Day in 2000).

'So my agent [told Sly's agent], "Arnold is talking to Roger Spottiswoode. And he's really into it. I think we're going to take the project,"' Schwarzengger recalled in a sneak peek of TMZ's special Arnold & Sly.

'And, then of course, his agent, knowing he's competitive with me — he can't let that happen. And so he then called the studio right away, "Look, you've got to give this to Sly! Don't give it to Schwarzenegger. Give it to Sly."

'And they said, "Fine." Sly got it and then he got the movie so I was, of course, in absolute heaven because I felt like the only way I could catch up with him is if he has a stumble,' Schwarzenegger added.

'Can you get more Machiavellian?' Stallone marveled.

The former California Governor added: 'I said, "We've got to go and have him have a failure."'

'Unbelieveable!' the Italian stallion exclaimed.

Stop! Or My Mom Will Shoot still managed to amass $70.6M at the global box office despite dismal reviews, and Sly received the worst actor trophy at the Golden Raspberry Awards for his role as Sergeant Joseph Andrew Bomowski.

Ironically, 1991 was the same year the Golden Globe winners first teamed up with Bruce Willis to become investors of the themed restaurant chain Planet Hollywood, and there are still three restaurants and four hotels in operation today.

'When we both invested in Planet Hollywood, we started flying around the world together to promote it and we became fantastic friends,' Schwarzenegger gushed.

'He is a great human being and we are now inseparable.'

Arnold and Sylvester have also costarred together in four action films: The Expendables (2010), The Expendables 2 (2012), Escape Plan (2013), and The Expendables 3 (2014). 

TMZ Presents Arnold & Sly: Rivals, Friends, Icons is scheduled to air this Tuesday at 8 p.m. ET on Fox, and it streams the next day on Hulu.

This month, the Terminator star —  who just had a pacemaker surgically implanted — will begin reprising his role as CIA operative Luke Brunner in the second season of Nick Santora's daddy–daughter spy comedy series FUBAR for Netflix. 

And Stallone — who allegedly mocked the appearance of background actors on Tulsa King — has been hard at work reprising his role on the second season of the Paramount+ dramedy as Mafia capo Dwight 'The General' Manfredi.