Well, somebody had to do it - it's that time of year ...

Okay, here's me query: I've got a St. Patrick's pub gig lined up for the first time in many years - got out of the game for awhile - so I'm wondering what people figure are the absolutely essential songs to know (we're talking North America here)? I don't mean, suggestions of Irish songs to fill up a night, because I know a million, and many of them are mentioned already on this thread, but what are the ones that you MUST be prepared to perform, unless you want to leave your audience disappointed, disgruntled, discombobulated, disgusted, dismayed, disrespected, and/or disdainful?

So, top of the list - Danny Boy. Next?