Messages sent from Discord which use curly apostrophes (due to autocorrect / keyboard settings making them that way most likely) aren't formatted correctly in Minecraft chat.

https://dl.dropboxusercontent.com/s/sl11gmdbytthzp3/javaw_0J8dlXmRQO.png

Scratch that, I forgot that months ago I installed a VanillaTweaks pack that had a different font in it, which doesn't have those characters it seems. Filed a report with them instead.