[Liam-]

Slow walkers.
Mouth breathers.
People who start a sentence but don't finish it.
People who say 'what did you say?' but go on to answer the question you asked before you can repeat it, they obviously heard what you said in the first place
Crumbs in the butter.
People not flushing the toilet after them, honestly just die.
People who put empty packages/cartons, back in the cupboard/fridge.
Taking things without asking.
People who don't respect your opinions just because you're younger than them.
Obnoxiously big umbrellas.
People who buy candles, but never actually uses them, my Mum does this and it winds me up.

That's all off the top of my head