Used in chats and conversations every day, "</sarcasm>" is used to denote sarcasm. In HTML programming, tages are ended with a "/", such as </b> for bold text. Usually one would say a sarcastic remark, and then use </sarcasm> to indicate that he has finished his sarcasm. It pwns your mom.

is a language spoken fluently in the country of Tumblr.

A term used to show what you have just posted is to be read aloud in a sarcastic tone. Comes from javascript or whatever it's called.

A word that gives you the possibility to play with your imagination when asked stupid questions.

Something that nobody on the internet can ever recognize.

1: The national language of Bolivia.
2: A species of small tree frog with a small red crest on its neck, local to South America.

Depending on how it's used, sarcasm can be a defense against stupidity or stupidity itself.

Stupidity: When someone asks someone else a decent question and they reply rudely with unneeded sarcasm.
Defense against stupidity: When someone asks a stupid question that more than deserves a sarcastic answer.