Wimmy wam wam wazzle! They're shamrock nails!
I used the small tutorial within this cutepolish video to make the shamrock (three hearts and a stem with a striper). I don't have any green items of clothing, so I was glad to remember to use some polish my sister gave me for my birthday before we went out to drink green beer tonight (and to avoid getting pinched, which is very rude and I'm still bitter about getting pinched when I was 16).
Happy St. Patty's!