How do you play that high? not that I want to, I doubt my ears could take it!! 
are there really tunes/songs that go that high??
The only one I know is an American Civil War-era fife tune, now popular among oldtime fiddle players, called āQuince Dillonās High D Tuneā. I guess you can guess the high octave note. You donāt want to stand near the fifer when this one gets played!
I have often questioned the existence of the third octave as well. How could one play that high? 
! I can hardly take the second octave sometimes.
I play into the 3rd octave when I play a song an octave higher then written, because i like the sound better, I dont mind the 3rd octave but i think my family doesnt apprecieate it all the time
There are some tunes in the Bill Ochs tutorial that go into the third octave.
Jason
I will sometimes play The Girl I Left Behind Me in the 3rd octave for a āfife & drumā kind of sound.
āJames
Thereās plenty of OāCarolan that goes into the third octave. The Fairy Queen and Hugh OāDonnell come immediately to mind. The only D whistle I have on which the third octave isnāt painful is the Burke Wide-bore Brass. Itās clear all the way up to the G.
That hurts me just to think about it.
Better watch out for your ears, is all I have to say.
M
the correct way to play the 3rd octave if far far away from people that you love.
I donāt particularly care for it. Even if you find a whistle that has a clear 3rd octave, I donāt find it pleasing to the earsā¦ just a personal opinion.
Earplugs. 
Earplugs! What is it with these musicians earplugs? How can you play music if you have ear plugs on?!
You donāt need to hear in order to make great music.
Case in point: Ludwig van Beethoven.
Sounds incredibly frustrating to not be able to hear music. No wonder Beethoven was so angry and eccentric. 
That was one of the points that really amazed me about my Susatos, the low end of the 3rd octave was VERY tight and easy to hitā¦
I put a part of a match lengthwise in the windway of my (Clare) high D and I blow easily the 3rd octaveā¦ when nobody is at home 
Mainly for instructional purposes, and completeness. Iāve yet to hear a GOOD sounding third octave. That third D is as high as I ever go.
We usually play a number of Breton tunes an octave up from written, which usually puts them mostly in the 2nd octave and in the lower part of the third octave. We play them a little fast, and the crowd always goes wild for them.
Musician earplugs arenāt met to block the sound, but rather to reduce the volume of the sound in a equal level accross the spectrum. Mine cuts the sound by 15db, with is the most frequently used sound reduction level. Drummers usually use 25db earplugs.
Also āMorgan Maganā