Very recent – month or three? Illyana Rasputin (Magik) goes back in time to visit Dr. Strange, to get magical help for a problem.
A joke ensues, which I can only quote roughly from memory.
“What about spell XYZ?”
“No, that is too dangerous, and could destroy the world.”
“What about spell HJI?”
“That invokes a malignant entity who might turn upon you and destroy you.”
“What about spell ABC?”
“Where are we going to get that many turtles?”
One of the best X-Men jokes ever, and I can’t find it now. Anyone able to tell me what title and issue number this was in?
Thanks!
Follow-up: found it. Uncanny X-Men 029.
My favorite X-Men-related joke comes from a completely different source. In the early-to-mid '80s, Don Simpson put out a comic called Megaton Man. He had a few merchandising items going, including this little gem. For those somewhat leary of clicking on links, it’s a button of Megaton Man, head, shoulders, clenched fist and gritted teeth, declaring, “Are you kiddin’? I eat X-Men for breakfast!” As I recall, Marvel was none too happy about it and slapped him with a cease-and-desist (the second one they lobbed at him, I believe, for a different issue), thus the button was pulled from the market.
I was always kinda bummed that I didn’t get one, but now I see that I can! Ah, nostalgia and the Internet! The perfect mix to make disposable income disappear! 
I remember Megaton Man! (“The Megatropolis Quartet! Golly, that crazy gizmo really works!”) Wonderful fun stuff!
(Also Wendy Whitebread, but never mind…)