My account was just locked. I received this message:
Your account appears to have exhibited automated behavior that violates the Twitter Rules. To unlock your account, please complete the steps below and confirm that you are the valid account owner.
What you can do:
To unlock your account, you must do the following:
Verify your phone number
This 100% happened because of all these giveaways that ask to connect to my twitter account before they give me a key. Just shooting this out there as a warning to others.