How do i deal with my sarcastic boss..-.-?

Your boss is a bully and is abusing his position to put you down. Try to find out what the company's policy is on bullying and harassment and how they deal with it for starters. If the place where you work is big and you have a Trade Union go see your representative. If not keep a journal, with date/time and exactly what he said. Did you get put on work experience by a training provider if so you need to report what is going on to them, if not you need to ring the Head Office and ask to speak to an HR Officer and tell them what is going on, because they may be able to get you transferred to another store, and dismiss the bully.