I have a... a thing about finger nails and I keep a clipper with me at all times and my finger nails are always trimmed.
Long fingernail freak me the Hades out and as much as I adore horror movies, watching The Ring, in particular, that scene where the girl without fingernails crawls out of the television not only makes me squeal like a school girl and curl up into a foetal position, it made me vomit. Any and all injuries or damaged nails will make me sick and I feel queasy right not having just remembered it. *Shudders*
[Edit]
I also refuse to shake hands with people who cracked nails and I have recoiled with looks of horror and disgust at girls with long fingernails. Ho boy, explaining why never stops being super awkward.