You Won't BELIEVE This Is Jennifer Lopez In Jimmy Fallon's Tight Pants -- Until You See Dat Butt!

Jimmy Fallon and Will Ferrell once warred over who had the tightest pants.
But against Jennifer Lopez, it’s not EVEN a competition!
Ch-ch-check out the video (above) to see JLo show Jimmy Fallon who wears the pants in the relationship- and listen as the audience finally realizes just who that is in those tight pants!