X-Men #44, May 1968
In Which We Learn That The X-men Need A Canine To Help With Shackle Key Retrieval, That When Warren Watches The Lord of The Rings He Creepily Insists On Using Slow Motion For All The Hobbit Scenes, And That To This Day Professor X Can Not Even Eat A Peanut Without Weeping For The Memory Of Sally, Linus, And His Little Red-Headed Girl!