These make me smile every time I hear them.
Seneca: Should be SE-ne-ka. Nigel says: suh-NEE-ka.
Salem: Should be SAY-lem. Nigel says: SAL-em, with A as in Apple. This one we really like and I think we'll say it this way even though it's wrong, kind of like how we never got around to pronouncing Euclid or Alvernon in Tucson correctly (to the bitter end, we said "Oy-klid" and "Al-VER-non").
Cayuga: Should be ka-YOO-ga. Nigel says: KAY-u-ga.
Triphammer: Should be TRIP-hammer. Nigel says: TRIFF-ammer.
Cascadilla: Should be kas-kuh-DEE-ya. Nigel says: kas-kuh-DILL-uh. It reminds me of Napoleon Dynamite every time.
Tioga: Should be tee-OH-ga. It took us a while to figure out why Nigel says: SHA-ga. Can you figure it out?
Here's a bonus one from our time in Utah: St. George. Nigel says: Street George. Nice.
My only fear is that I'll start reproducing these odd pronunciations in my speech and really embarrass myself in front of some Ithaca old-timers.