Apparently, you haven’t really mastered the English language until you can be sarcastic. Sarcasm can be tricky, even for native speakers but I just found this very useful guide from the BBC which should enable you all to display this lowest form of wit at every opportunity! If the concept of saying the opposite of what you mean to reveal your true feelings still sounds complicated, you can always resort to Wayne’s World for an easy solution. This film introduced a particular usage of the word ‘not’ to a worldwide audience and this is sarcasm in its simplest form. Here are a couple of examples for you:
classic British sarcasm: I absolutely love getting my tax bill.
Wayne’s World sarcasm: I love getting my tax bill – NOT!
Whichever method you go with, get out there and have fun with it!