By the pogues/traditional

for g pennywhistle: (although it might be easier to tell teh rest of the 
band to play it in the key of your pennywhistle than buying a g one)

underneath finger indications, + equals highest octave, - equals lowest 
octave, nothing underneath means the middle octave

|x o x x x x x x x x x x x x x x x x x x|
|x o o x x x x x x x o x x x x x x x x x|
|x o o o x x x x x x o o x x x x x x o o|
|x o o o x x x x x x o o x x x x x o o o|
|x o o o o x x x x x o o x x x x o o o o|
|x o o o o x o o o x o o x x x o o o o o|
+                   - -

|x o x x x x x x x x x x x x x x x x|
|x o o x x x x x x x o x x x x x x x|
|x o o o x x x x x x o o x x x x x x|
|x o o o x x x x x x o o x x x x x x|
|x o o o o x x x x x o o x x x o x x|
|x o o o o x o o o x o o x x o o x x|
+                   - -