My mom sometimes slurps too loud when eating soup, which irritates me, but I've become accustomed to it.
When my grandma sees me cooking, she goes from your typical "it's nice that you can cook, I'm so proud" to <insert what you're doing wrong here>. It irks me especially when I'm using asian or non-conventional ingredients. Like, who the hell would she know?
One of my best friends has a tendency to be late all the time. And as a very punctual person myself, it annoys me when I have to wait somewhere just standing and doing nothing and he texts me "I'm on my way" 10 minutes after the scheduled time.
Note that I love and care dearly for all of the people mentioned.
As for my bad habit, I don't really burst into laughter and instead just blow the air through my nostrils when I laugh. My brother hates that, but there's not much I can do about it.
I most likely do something else that's annoying someone, but I can't think of specifically anything else.