yn or (yn) is an msn emoticon which resembles fingers crossed. people use this differently, it can either mean that youre tight with someone as in really close friends or people use it when they say goodluck.
1. girl one: i havent seen jenna in ages!
girl two: really? i saw her last night! were (yn)
2. guy one: i think im going to see if i can get an extension on my english assignment