You are Not Allowed to Tweet Until You Pass This Test
When you tweet, your words are open for the entire world to see. What you tweet reflects you, both personally and professionally. With that in mind, typos are always a stain on your reputation. And while most will forgive accidents—we're all human—poor overall spelling, grammar, and punctuation will not serve you well.
The internet has allowed for more leniency than in the past, but please, know the basics. The Oatmeal has been kind enough to create a 20-question Twitter Spelling Test to prevent embarrassing "mistweeting."
If it were up to me, I'd have Twitter require that all users signing up score at least 90% on this test before they're allowed to tweet. But it's not. Still, it wouldn't hurt you to see where you stand—after all, this isn't Facebook. There are standards to uphold!