On the plane, George went over to talk to Jerry. He said that Jerry had been his best friend since the 4th grade. But in "The Outing," George and Jerry outlined how they had met - in high school.
George was climbing the ropes in gym class, and Jerry was spotting him. George kept slipping and burning his thighs on the rope, and finally he fell right on Jerry's head. They've been close ever since. :-)
Michael Alexander