Given that their past year has essentially been a collection of "can't believe it" moments, you'd think that Imagine Dragons would be used to having their minds' blown ... but you'd be wrong.

Turns out, stuff like touring the world, scoring a crossover smash, stealing the show at the Grammys (not to mention actually winning the award for Best Rock Performance) and scoring a spot on "Saturday Night Live" pales in comparison to paying tribute to the Beatles ... which they did Sunday, as part of a star-studded special that marked the 50th anniversary of the Fab Four's iconic first appearance on "The Ed Sullivan Show."

Seems that no matter how much they've achieved over the past 12 months, the Dragons still weren't prepared to come face-to-face with the surviving members of the legendary group. Which is why doing something like "SNL" immediately afterward really didn't faze them all that much.

"The funny thing is, I think we would have been way more nervous for [their 'SNL' performance] if it wasn't for the fact that we had just done the Grammys, and then after that we did the Beatles tribute," frontman Dan Reynolds laughed. "That was the most nervous any of us have ever been, because you're performing a Beatles song in front of Paul and Ringo ... and that's just so intimidating."

"It's crazy that the three most high-pressure gigs of our career all occurred in one week," bassist Ben McKee added.

So with the Grammys, 'SNL' and an up-close-and-personal audience with McCartney and Starr out of the way, is there anything that can stop the Dragons? The answer would appear to be no ... after all, they've basically lost the ability to be nervous at this point. Call it evolution.

"Whatever gland in the human body that produces the chemical that makes you feel nervous, that gland has died in all of us," drummer Dan Platzman said. "'SNL' was a dream come true for all of us ... and when the moment came it was just so natural, and that freaked us out. Like, 'This shouldn't seem so natural.'"