George Thorogood & The Destroyers - I Drink Alone... link
Aerosmith - Dream On (I can't do the high screams at the end, though)... link
Brad Paisley - Alcohol... link
I have a friend who also likes to do karaoke. She and I do awesome renditions of Need You Now, Whiskey Lullaby, and Wanted Dead or Alive.
What are yours?