I have a bit 'o the Irish in me, too! One-quarter, to be exact!
While most Americans celebrate St. Patrick's Day by getting blitzed out of their mind, I've always seen the day as a celebration of heritage - given what the Irish have gone through. And boo hoo to your humbug co-worker, Alex - you should let him know that they celebrate it in Ireland with festivals, and the like - he can google it, or just follow
this super easy to find link about a festival. It seems at a first glance they celebrate with parades and feasting with a bit 'o beer.
I should add, my favorite St. Patty's Day tradition: Corned beef and cabbage. Who's gonna make me some?