It's also worth noting that the idea of stopping the bouncy kind of waves is just stupid. Waves that reflect will pretty much never give you cancer. The ones you need to worry about are the waves that soak into things. Microwaves and radio waves bounce off walls and mountains and clouds and they never seem to hurt anyone. Dangerous light like sun light doesn't reflect; you can stop it by putting something opaque in front of it like an umbrella or a computer case or clothes or....
Ground is an interesting term in engineering, as it doesn't exactly refer to the physical ground, but a large conducting plane with low resistance. I think in general all that's required of 'ground' is a large conducting surface for charges to spread out on and thus minimize the field strength. Your cellphone has a ground plane.. it's not connected to 'ground'
Grounded often means something is tied to the neutral voltage. In your house you have a black wire, a red wire, and a white wire. Black to red is 240V, and white is in the middle at 120V to either of the other two. White is the neutral point. Green is electrically the same as white. Things are grounded because they are tied to green, which is tied to white, which is neutral between red and black (and sometimes blue). DC ground works the same basic way. Green would be thought of as 0 or neutral, red is positive relative to green, black is negative relative to green. Tying things to the DC ground means you know what the voltage is between grounded things and hot things; no more floating voltages and signal interference.
So then what happens if you tie things to the red wire instead of the white or green wire? Well then it's not grounded. It's hot. If you want to get technical, then tying
everything in the world to the same hot line would work, but we don't do that because it's needlessly dangerous. If you get a ground fault from red to white or black to white, it's just 120V. If you tied everything to red, then a fault against the black wire would be a 240V fault. That's much much worse. It's safest to "ground" things to whatever electrical point is the most neutral. That keeps the voltages as low as possible when things go wrong.