My car doesn't over heats but when I took my cap off of my radiator the stuff came out and my co worker said I should get a radiator flush

If the engine was hot, or still warm, coolant will come out of the radiator due to expansion of the coolant. You never want to take the radiator cap off when the engine is hot, only when it is cooled down.

The cooling system builds up pressure when it is hot.

For every lb that is listed on the cap, it increase the boiling point of water. When you shut your car off and you have a temp gauge. Turn the key to on and don't start it. The temp gauge should rise as it is no longer circulating and being cooled. You should never open your radiator cap right after shutting off car. Boiling point of water if I remember right is 212%. Take a radiator cap that holds 14 lbs of pressure. Take that 14 by 3 and you have changed the boiling point of water to 254. When you take the cap off, the water goes right back to 212% and that is why some people get burnt, because the water just blows out. Keep it running and take a hose and run cold water over the radiator to lower the temp. The temps on the new cars run a lot higher than older cars. Never take a cap off is the engine is hot.