How to speak incorrectly? URGENT!?

Get a book called American Slang, get drunk, then do your play. Get a book on Southern slang and regional dialects, 'cause anything out of your normal region will sound different. When I moved to Colorado, some co worker morons here thought I had a Southern accent,, I grew up in Miami, no Southern accents there, I just had dumb boss, real dumb, still dumb. You could search speech therapy to see how they teach people to relearn words.. or how loss of hearing affects speech. Just put cotton balls in your mouth, talk like Marlon Brando in the Godfather.. I hope your intent is not to be funny. It's an extremely sensitive area for many people for all kinds of reasons that they cannot help.