Unfortunately, it seems no one ever measured Iron Mike's heavy hits with a punch-o-meter like the one Drago used in Rocky IV. But they did measure those of his rival Frank Bruno—who was estimated to land 1,420 pounds of force in the ring.
Even though Bruno represented two of those 44 knockouts, let's assume Tyson's blows were pretty much equal. If we take that force and assume that he could produce that force for just under a foot, we get around 1,178-foot-pounds, or, 1,600 joules of energy (Rocky Marciano was measured at 925-foot-pounds).
So what is it like getting hit by 1,600 joules of Tyson? It'd feel like...
Getting hit with a 221lb anvil dropped from 5ft.
Or having Simon Cowell crash into you on a Vespa at nine miles per hour.
It'd feel just like a dorm refrigerator filled with three 12-packs of ice cold beer falling out of a second-story window.