Mark Ruffalo’s propensity for spoilers is, at this point, beyond a running gag, even though, so far as we know, he’s been on his best behavior regarding Avengers: Endgame. And while that joke may be losing its luster, this one still got a few laughs out of me.
Source: io9 – Jimmy Fallon Gives Mark Ruffalo an Avengers-Related Lie Detector Test