Your phone's autocorrect feature is notoriously funny/torturous at times. Here's one instance where autocorrect comes in handy: Have autocorrect type in the apostrophe for you for contractions, so you don't have to switch to the other keyboard to do it yourself.
Here's how it works: Repeat the last letter of the contraction so it's misspelled, e.g., "weree" instead of "we're". The iPhone will know you meant to say "we're" and not "were" and replace the misspelled word. This comes in very handy for contractions that could be auto-corrected to similar words ("we'll" vs "well") and could be a big time saver.
This video from the Tripp & Tyler Show provided today's quick tip and also offers another one: To get someone to stop texting you, send them and SMS error message. (You're probably better off blocking the person though.)