The G in GIR stands for

GIR
GIR is a malfunctioning robot built by the Tallest to accompany Zim on what they hoped would be Zim's banishment. The unit introduces himself as GIR, and when asked what the G stands for, he cheerfully responds "I don’t know."

G stands for

 * Garbage
 * General
 * Generalist
 * Generic
 * Good
 * Goofy
 * Great
 * Groovy
 * Guard
 * Guardian
 * Godly