O'Shea will reach the landmark against Germany on the weekend.
He said: "My 100th cap could come against the world champions, so that's a nice game for it to happen. I'd only be the sixth Irishman to do it as well.
"It will be something I will look back on more when I have finished in the game and not playing. It will be special at the time for my family, friends, old clubs and a very proud moment."
For the big stories and the banter follow us on Twitter: @tribalfootball