Word I Hate*: Persons. Just say people, ok? I don't care that there's a slightly different usage. 'People' usually does the trick. Use it.
Rule I Hate: To not split infinitives. Splitting's more natural.
What word do you hate?
What grammar rule?
Up with what sort of errant pedantry will you not put?
*Hate is so far beyond the mild annoyance I actually have for these things, but it's more fun to pretend one hates things for conversation. Feel free to scream away about your hated grammar points.