"Top of the Morning to You" is a a traditional Irish greeting that is often associated with St. Patrick's Day. When you say "top of the morning to you" to someone, you are wishing them the best part of the morning. The traditional reply is "and the rest of the day to yourself.," wishing them a good rest of the day.
"The Wearing of the Green" is another phrase associated with St. Patrick's Day, and it is common to wear green on St. Patrick's Day. "The Wearing of the Green" is an Irish ballad lamenting the repression of supporters of the Irish Rebellion of 1798. It is to an old Irish air, and many versions of the lyric exist. The song proclaims that "they are hanging men and women for the wearing of the green".