Possible a reference to "**** licking". If you are said (figuratively) to "lick someone's ****" or "suck up to" someone, you are trying to ingratiate yourself with them.
Hence, if somebody is sick of your obsequious behaviour, they might ask you to stop by using this crude expression!
Hi, I saw this in Friends. The boss of Rechal asked her why Chandler did not call her (the boss) after their first date. Sophia said:"Maybe he is intimited by a smart, strong and successful woman." Then the boss said:"Please climb out of my ****." I guess Eimai's is the answer. This is so funny. In Chinese, we actually have such a smiliar expression which is "to tap (one's) horse ****."