1
general::
Phrase(s): Beat it!
Inf. Go away!; Get out! • Bill: Sorry I broke your radio. Bob: Get out of here! Beat it! • "Beat it, you kids! Go play somewhere else!" yelled the storekeeper.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Go away, as in We should beat it before the food's all gone. This term is rude when used as an imperative, as in Stop pestering me?beat it! [Slang; late 1800s]
American Heritage Idioms