An instant fail if you use it to help you with your homework. I learnt this the hard way, and when I used it for my 5th class (the equivalent of 5th grade for all those Americans reading this) project on space, I only passed because my dad said it was all bullshit.
Me: Hey dad, is it true Earth is 5,750 years old?
(Dad collapses and rolls around on the floor, laughing)
Dad: Where'd you learn that shite?
(Dad drops to the floor again and rolls around laughing...again)
Although it's the most fail-proof method of contraception, it's also the least fun. The word abstinence can mean refraining from something, e.g. abstinence from alcohol or drugs. But abstinence from sex is about as fun as watching paint dry. Various groups promoting abstinence use propaganda to get their way, such as videos of a couple having sex getting covered in horrible sores and dying in flames.
Abstinence group: Abstinence gets you into heaven! If you have sex outside of marriage, God will give you herpes, AIDS and all sorts of STDs!
Anyone with a brain: God doesn't give you herpes, unsafe sex does. Just use a fucking condom!
A person fascinated with the Irish language and insists on speaking it 24/7. A Gaeltard will insist in their name being written in its Irish variant, e.g. someone called Declan calling themself Deaglan. Will also scar their children for life by giving them a weirdo Irish name which means something completely random in English, e.g. "Sneachta", which means "snow".
Person 1: "Conas ata tu?"
Person 2: "Get away from me, Gaeltard!"