Add a bounce effect to the object.
n = 0;
if (numKeys > 0){
n = nearestKey(time).index;
if (key(n).time > time) n--;
}
if (n == 0) t = 0;
else t = time - key(n).time;
amp = 40; // bounce height
freq = 4; // bounce speed
decay = 3; // how fast it settles
value + [0, -amp*Math.sin(freq*t*2*Math.PI)/Math.exp(decay*t)];