Can You Start a Sentence with "Because"?

You can start a SENTENCE with 'Because'. We are talking about a sentence—not a sentence fragment or a dependent clause.  

Can you start a sentence with 'Because'? Yes, in conversations and informal writing, where conventions don't matter. 

You must have listened to hundreds of dialogs in movies where characters say the effect first and then explain the cause with 'because' after a pause, which leads to two separate lines/sentence fragments separated by a period in the subtitle.