Writing

Who ever invented slang. Because "slang" is like a second language using proper grammar is so hard. Everyday we go around shortening words and talking to our friends this way. So when you have to switch modes and use proper grammar its very difficult. So back to my main question who invented slang. And why is the writing process so difficult. But then if i look at other languages its nearly as complicated as others, lets use Spanish as an example. Spanish has different sounds for feminine and masculine items. So does this make the writing process hard or just make me lazy?