Watch Mark Ruffalo take an Avengers: Endgame lie detector test on The Tonight Show

Mark Ruffalo is known for something among the Avengers cast, and it's not for being tight-lipped. Ruffalo is one of two Marvel Cinematic Universe stars (along with Spider-Man Tom Holland_ who's become notorious for — accidentally or otherwise — dropping spoilers for upcoming films in various interviews.

He dropped a massive one for Avengers: Infinity War in a now-infamous interview all the way back in 2017, and as a result he's become a bit of a target for both fans and fellow celebrities looking to have a little fun with Marvel Studios' famous policy of secrecy. 

Jimmy Fallon's Tonight Show has become particularly fertile ground for Ruffalo to have a little fun with his own reputation of late. He appeared on the show last fall and "spoiled" the then-secret Endgame title as well as various other details for the studio audience, while the show bleeped his words and put a black box over his mouth. Ruffalo appeared on The Tonight Show again Wednesday, and once again Fallon put him through an elaborate comedy bit tied to Avengers: Endgame.

This time around, after revealing that he is forbidden from giving interviews for the film alongside Holland (Marvel said "absolutely not," according to Ruffalo, and paired him with Chris Evans instead.), Ruffalo consented to taking a lie detector test administered by Fallon, complete with a flashing red light to let the audience know when he's lying. Is it legit?

Probably not, but it's still fun to watch Ruffalo squirm when Fallon asks if the Hulk is secretly a Skrull, or if there are clues in the latest Endgame footage that fans still haven't deciphered. And it's particularly interesting to watch Ruffalo's response to the question the audience clearly wanted an answer to more than any other: "Do Bruce Banner and Black Widow finally get together romantically in the new movie?"

We'll finally find out the answers to some of these questions when Avengers: Endgame hits theaters April 26.