A horrible/awesome document markup language. You can make your scientific documents and mathematical proofs look flawless at the small cost of several tedious hours per page (no exaggeration.) This time is usually spent googling how to do simple things like align text or figures. Often, the exact same problem has been posted in forums by equally frustrated individuals across the globe who also can't seem to figure out what should be intuitive but instead involves including some random package in your document's preamble. The problem with LaTeX is that the result is so great that once you start to use it and decide it is totally not worth the time, it's too late and you are in love with the pretty equations it can make and it devours your time (because you had lots of free time as a physics/engineering/grad student?) Now you can stay late at night in your office to work on papers and proofs. However you will likely get frustrated and distract yourself from preparing said documents, and end up browsing sites like The Chive and writing lengthy urban dictionary definitions.... oh wait.
a:Hey man, do you want to do fun social things with our social group tonight?
b:No I'm good. I have another paragraph to format in LaTeX, which will take me the next 6 hours or so.