Explanation: You are not telling someone to literally get out. This is a common idiomatic phrase to express disbelief. Often times it is used in a positive way as in the first example sentence below.
Invata engleza mult mai REPEDE descarcand versiunea offline pentru TalkEnglish si vei avea peste 8000 de fisiere audio si peste 800 de pagini in lectii! Apoi poti sa studiezi fara sa folosesti internetul si sa asculti fisierele audio MP3 oricand. Mergi la pagina Descarca lectii de engleza si descarca astazi!