What you say to someone who is being incredibly condescending or arrogant about her supposedly superior intelligence. Literally, You are a horse's ass. Example: Well, Mr. Buckley, in the words of Horace, or was it Yoggi Berra?: podex equis est.
PODEX EQUIS EST
Meaning of PODEX EQUIS EST in English
Slang English vocab. Английский сленговый словарь. 2012