1. You've heard this one before. Important People Don't Die in One Piece.
It really doesn't matter how many limbs are cut off, or how much blood is lost, important people or those utterly vital to the plot can not die. Oda refuses. Don't complain.
2. Dust
No matter how clean or kept something is, Hell, the place could have like 10,000 maids around, dust, smoke, God knows what will come out when characters slide their feet along the ground or straighen their position.
3. Comical Relief Overpowers Logic
For the sake of making a joke, many physical laws will be broken in this attempt. Whether it's having someone sleep through a train crash, or having someone punch someone as hard as they can for humor, while other punches would normally break daimond, the person is still fine and alive, the jokes aren't even that comical anyway.
At least not until the second time watching, in which you go "Wait, what the fuck?"
4. Usopp Will Never Change
There's really no explanation for this. 417 Chapters and he's not doing to great with the change. It aint happening. Get over it.
5. Luffy Will Always Get Stuck
Buggy Arc: Stuck in a cage.
Kuro Arc: Lost in the forest
Arlong Arc: Stuck in Cement
Little Garden Arc: Stuck under a giant skeleton
Alabasta Arc: Stuck in Quicksand/ Sleeping
Skypeia/Jaya Arc: Golden Bell/ Snake
Water 7: Stuck in a Chimney
6. Women Will Be Victims
I think we have yet to have a strong female that's not utterly manly or secretly male. All attractive females are victims… of something. Anything.
6. "To Be Continued" Screens Pretend to be Unpredictable but They're Not
If you've been watching One Piece for a long time, you'll be able to predict these things left and right. Also, when you have the soundtrack memorized (They've used the same tracks for 10 years), you'll be able to time the last "DUN" of the song and the "TO BE CONTINUED" screen will play.
They occasionaly put the "BUM" or "DOODILIDILIDOO" sound effects at the end to say "Oh, we got you! This is a surprise! BOO!", but by then, you already know and decide to exit VLC and click the next file.
7. Marine's are Dumbasses Most of the time, many marines will just run around as a group, having no mind of their own, and losing all common knowledge. If a bullet didn't work the first time, why do it again? How stupid could you be?
Also, they follow orders like mindless, little, drones.
Marine's sole purpose in One Piece is to relieve stress (We tend to take everyone who isn't an admiral far too seriously), crack jokes, and otherwise, be beaten as a crowd by Luffy.
Has there been a single arc in which Luffy didn't beat the shit out of marines and then they all went nuts?
8. The Villian will meet a Terrible Fate but Still Live, Shoving the Entire Arc Potential Down the Drain Despite how many people he killed, how maybe kittens he's eaten, and how many Wii's he's destroyed, Luffy will never kill the villian, more so deal an extremely dragged out and over-emotional blow that will sometimes last up to minutes if not multiple episodes.
9. There is no spoon No matter what.
10. **The More Defined Someone's Facial Features are, the Less Important They Are to the Story
** True fact. The crazier the face, the less important to the plot. See, Luffy has a normal face. No terrible, bloody scars, no rotten skin, no big nose, while people like Bon Clay are just plain ugly. Also, Sanji's curly eyebrows are just a way for Oda to tell us that Zoro is more important without using words.