Means, "I'm too lazy to formulate a response or type for myself, so I'll just put 'X2'a to denote I agree with you."
And all this time I thought everyone was referencing the X2 Chi-square distribution from inferential stats. Huh.....Ohhhh, forgot the context. Everyone is actually talking about Evel's Skycycle X2. That's the one that jumped the canyon but the chute deployed early. That man had balls the size of Dood's old Prius. No brains. But Prius sized nads!
X2: The interface used to interconnect eNodeBs.