Green Lantern #138 (July '01)

"I got a call two days ago from J'Onn J'Onzz, the Martian Manhunter. He wanted me to go to a planet in another galaxy. Yes. I get calls like this."

"It is called Tendax and they need an ambassador for a very auspicious ceremony. They contacted the JLA seeking the Green Lantern."
"Hal Jordan, huh?"
"Yes. I told them he was unavailable."
"And you told them about me."
"Yes."
"Then they asked for Superman."
"Yes."
"You said he was busy."
"Yes."
"Then they asked you to come."
"Yes."
"You declined."
"Yes.
"For the sake of time let's just pretend they asked about me next."
"Fair enough. Are you interested in going? It would only be for a week"
"Can I bring my girlfriend?"

And that's all a Martian Manhunter fan needs to know about that issue, by Judd Winick and Dale Eaglesham: