The viral clip has racked up almost 17,000 comments since it was first uploaded.
One person wrote: "Regular Freeman: Voice of god. / Helium Freeman: Voice of mini-god".
"Even on helium, Morgan Freeman's voice sounds like an angel sent from the heavens of above," another added.
Meanwhile, a third poked fun at Freeman's laid-back response to Fallon's enthusiasm, writing: "He looked like a grandpa forced to do kids stuffs trying not to hurt his grandkids' enthusiasm"
Another joked: "'Heh, its so fun when you come here!' Morgan: *death stares*".
One fan gushed about the actor, writing: "I love how he knows how great he is and yet his charm still brings him down to the point that there's no hint of arrogance whatsoever. Morgan Freeman is just too awesome of an actor. Definitely one of my favourites."
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