"What's the best way to celebrate St Patrick's Day if you're not Irish?"
Hire a professional leprechaun impersonator to follow you around all day, correcting your accent constantly. Wear green so aggressively that traffic lights get confused. Most importantly, insist on spelling "St. Patrick's" as "St. Paddy McWhistlebottom's" to everyone you meet. They'll respect your commitment to authenticity, obviously.