"MN lingo" that starts out being quite endearing but through massive overuse just becomes the equivalent of "baaa"
fanjo, did you mean to be so rude, entitled etc
and especially "no is a complete sentence". well yes but it's a very rude sentence in most situations. "Sorry to ask but could you pick my kids up from school on Tuesday while I go to the dentist?" "No."
people who capitalise food "today we are having Shepherds Pie, Apple Crumble and Custard". I hope it fucking chokes you.
people who report posts that are not hurting anybody 
using lol instead of a full stop eg "Oh no I don't think I could do that lol"
"perky" thick people who use lots of !!!!!!!
people who post the same fucking thing on every single thread regardless of its relevance. Shove off. Start a really dull blog that nobody will read.
"ladies", "girls", "girly", "girly night in/out"
Most of the post and anti-natal thread titles, they are shit attempts at rhyme with no effort at scansion, they are not funny and they never will be
"there" instead of "their" eg "anyone had there LO do this?"
that will do for starters