Three lines, real simple:

tell application "iTunes"
duplicate current track to playlist "srsly partytime"
end tell

And then you can create a Quicksilver trigger to run the script; so, anytime you hear something and think “yo, that’s my JAM” you don’t have to leave the keyboard to make sure it gets in the rotation for your upcoming birthday party. A couple of tracks that should be on there right now:

  1. Crystal Castles – “Crimewave
  2. Foals – “Olympic Airways