How much effect would two billion people jumping at one time, in unison, have on the earth? Earthquakes? Falling out of orbit? Absolutely nothing?
How about almost two billion?
Work = force * distance, and force = mass * acc, so potential energy = mass * acc * distance. A 70KG adult
jumping from a 1/2 meter chair in a 9.8m/sec^2 gravity field releases 340 joules of energy. Two billion of these would release 6.8x10^11 joules, which is equivalent to an explosion involving 0.16 kilotons of TNT (way smaller than the Hiroshima bomb)
How much energy in an earthquake? I was under the impression that even a small earthquake packed way more energy than a nuke.
I think you want your 2 billion people to form a large circle surrounding their target. 
Then when they all jump, they’ll launch a surface wave inwards, and the wave will grow very large because it’s focused on a small area.
This is like the “duck-annoying museum fountain”