To sign "thirsty" run the tip of your index finger down your throat.
CRAVE: You can modify the sign THIRSTY a bit by using a more
intense facial expression and a bit more of a deliberate movement which
changes the sign to mean "crave."
Also see: HUNGRY
You can learn
American Sign Language (ASL) online at American Sign Language University ™
ASL resources by Lifeprint.com © Dr. William Vicars