So I was riding today and the chain fell off my rear cogs twice during the ride here are the conditions of both times:

1. I was flying down a big hill and was in the highest gear spinning as fast as I could and it popped off (towards the derailleur)
2. I was going up a really steep hill maybe an hour later and switched to the lowest gear and it popped off (towards the wheel)

Anybody have any idea why this might happen and if there is something I can do to keep it from happening (or maybe its a technique issue )? Thanks in advance for your help.

we probably need more info about what type of bike and the setup, but my first guess is usually a bent derailleur hanger, or perhaps a dirty chain in need of a good cleaning.

Odds are that neither limit screw is properly adjusted.

Let's start with the second incident, over-shifting into the wheel.

Step one, verify the inner limit screw adjustment by shifting to low pushing the lower RD body in while pedaling. Keep pushing after it's in low and see of you can cause the over shift. If so, the inner limit needs adjustment.

Similarly, check the outer limit. Shift to high gear, and use the barrel cable tensioner to loosen the cable until it's slack. Pedal and check that the RD doesn't move too far out. If it does, the outer limit is off.

I suggest you find a tutorial on RD adjustment, and carefully review the sections on adjusting both the inner and outer limits. When the limits are properly set, then you can use the cable adjuster to get the shifting dead on.