The video – aptly titled 'Baby's First LOL' – has been viewed more than 2.2 million times and shows the dad lifting his baby aloft and bouncing him or her up and down.
The three-month-old is the first to start giggling, sounding like a squeaky toy, then dad soon gets the sniggers and guffaws before they both descend into hysterics.
At one point the dad is so convulsed he has to wipe tears from his eyes as he says to his baby: "You are adorable. This is your first big laugh [do] you know that? This is your first laugh!"
The baby's mother is also heard laughing in the background as she captures the moment of hilarity on camera.
One viewer on YouYube remarked: "I think this could keep me happy for days."
We second that!
p.s. *ROFL means 'Rolls On the Floor Laughing', which is what we're doing right now.