If you're all 'I have no idea what you're talking about, Taylor', synesthesia is a condition where you associate one sense with another (example: the drums taste like licorice when you hear them, or when you drink coffee you get the sensation of cement), or you assign personality, colour, location or sense with letters, numbers, weekdays, months or words (examples: Friday is always purple and/or tastes like chocolate and/or is always located somewhat behind you to the right when you think about it and/or is a bit of a flirt). The wiki entry is here if you're still confuzzled (which you probably are as it's something sort of hard to explain).
You can find out if you have synesthesia here and you can do the synesthesia tests there as well. Her request for help is here, with instructions on what she's looking for and how to help her out. It's kind of a fun thing to do, so you might want to check it out. It's like all those popular personality tests that people blog about.
I'm a bit curious about all this myself, now, so here's a poll for my f-list:
Do you have synesthesia?