If there's an individual song you don't want included in your iTunes shuffle or Party Shuffle options, find that song in your iTunes library. Highlight it and then Get Info. Do this by going to the File menu and choosing Get Info. You can also do this on the keyboard:
On Window: Control + I
On a Mac: Command (the Apple key) + I
This pops up a window with information about the track. Choose the "Option" tab at the top of the window.
On the Option page, the second-to-last checkbox reads "Skip when shuffling." Check that box and then click "OK."
That song will no longer pop up in your shuffling.
