It's understandable for a public school administrator to want a li'l drinky-poo after a hard day's work dealing with the kiddies, but driving to school sloshed? Those kids at IS 217 in the Bronx must be monsters! Assistant principal Melonie Lendor was arrested on the New York State Thruway in Rockland County at around 6:40 a.m. yesterday after other drivers called 911 because she was driving so erratically. Police say she failed a field sobriety test, but refused to take a Breathalyzer test. Worse: Her 10-month-old son was in the car. Still worse: This is her third drunken-driving bust. That means she's (finally) charged with felony driving while intoxicated and child endangerment. A seventh-grader at the school tells the Post, "No wonder we didn't see her today," but students should probably be used to that by now; a teacher tells the Daily News, "She was entirely missing from the school at times. She seems to make bad decisions."