If you've got an Android and use the default keyboard, you can get rid of autocorrect words that you would never say or misspelled words that your keyboard has learned over time. All you need to do is take out the trash.
First, check to make sure you have the 5.0 update or better. Go to Message+ and open it. In the upper left side, tap on the Menu icon and select About from the menu. A screen will pop up and tell you what version of the app you have. If it's 5.0 or higher, you're golden.
Now, pop on over to a text message conversation. Autocorrect learns from what you type. So, if you constantly misspell a word it will think that is what you want and will put the word in its dictionary.
Whenever you autocorrect tells you to misspell something, tap on the suggested word and drag it upward. A trashcan icon will appear at this point. Just continue to drag the offending word over to the trash can icon and release it. That word will be deleted and will never come back...unless you teach your autocorrect that word again.
While this works with the default keyboard on all types of Android phones, it may not work if you are using third-party keyboards. For example, on SwiftKey you can drag a word up to remove it, but the trashcan icon won't appear. You'll just get a pop-up asking you if you would like to remove the word from the dictionary.
This is particularly handy for those of us with salty language. I will never say "duck" in conversation, even though autocorrect is constantly telling me I should. Finally, I got tired of the motherly advice and chunked duck in the trash. Now I am able to cuss freely. Take that, autocorrect.