One of the hallmarks of being a great actor or actress is the ability to cry on cue. It's definitely not easy, but all the big Hollywood stars know how to pull it off, ultimately adding a more honest and emotional layer to their performances.

So how do they do it?

Well everyone has a different trigger -- and while you'd think it might be more difficult for a big, burly tough guy like Dwayne "The Rock" Johnson, you'd be mistaken. In fact, all it takes to make the Rock cry is... well, a little Whitney Houston.

While speaking to the New York Times in advance of San Andreas, which arrives in theaters this weekend, the Rock revealed that he can indeed "cry like that," adding... "I hear a song sometimes, ‘Didn’t We Almost Have It All,’ by Whitney Houston, and..." the Times then notes that "his face crumpled into sadness." 

Say it with us... "Awwwwww!"

Johnson goes on to admit that the thought of losing his own daughter and loved ones also adds some dramatic weight to his crying skills, but Whitney -- oh, Whitney -- is always there to bring the biggest of all boys to his knees.

What song gets your tears flowing? Chime in below.