I pretty much hate about 90% of word abbreviations but there's a few that really grate my nerves and one in particular that I keep seeing is "Grats!" i.e. someone posts some good news and then every friend on their friends list posts identical "Grats!! xxxx" underneath as if saying 'congrats' is too long and time consuming to type, let alone 'congratulations'.
See also: 'choccie', 'biccie' and worst of all when they are used together (GAG). Also 'hubbie'.
Urgh, now you.