That title is one of the most famous lines in one of the greatest buddy movies ever made. Buddy movies have been around for ages now, harking back to the days of Laurel and Hardy, Abbott and Costello, and (my personal favorite) Bing Crosby and Bob Hope.
Looking back at thirty some years of comic reading I'll have to say that Marvel has had its fair share of great buddies as well. Probably the longest and oldest would have to be Human Torch and Spider-Man (which is pretty odd since they are both in their late twenties and their friendship has lasted nearly fifty years). But with Johnny Storm constantly off in space or the Negative Zone and Peter Parker erasing everyone's memories every ten years so he can reveal his true identity all over again, they don't really hang out as much. They may have the oldest friendship, but not the strongest.
Then there's Luke Cage and Iron Fist. Now these guys have had a very strong and powerful friendship that has had more ups and downs then the Chicken Ranch. It's unfortunate that they've been split up by that darn Jessica Jones. Leave it to a woman to ruin a great bro love like theirs.
I could really list a ton more that Marvel has had, including my personal favorite: Beast and Wonder Man, but if I had to call one friendship the best that Marvel has ever created, I've got to go with Nightcrawler and Wolverine. A highly spiritual and religious mutant with the looks of a demon and a Canadian killing machine seemed the least likely of friends; but since the late seventies their friendship has remained one of the most honest and compelling that Marvel has ever offered.
Kurt Wagner was repulsed at Logan's blood lust when they first became members of the X-Men and Logan found Kurt's spirtuality and kindness to be out of place in a world where they were a hunted and hated species. Yet, from their first adventure together way back in Uncanny X-Men #129 when they fought the Wendigo, their friendship blossomed and has grown ever since.
Through the years every writer has seen the special bromance that these two have carried for each other and have made sure that at least one issue focuses on it. Occasionally they will throw Colossus in the middle just to shake up the dynamics, but even then, it's all about the demon and the animal.
I think we can take away a lot from this long standing friendship. They've proven that you don't have to have the same belief system to become best friends, you just have to see the heart of each other and work to nurture it.
There's a plaque that a friend of mine from high school, and who I am still very close to, gave me once. It reads: A true friend understands your past, believes in your future, and accepts you today just the way you are.
That's Kurt and Logan. That's my buddy Larry and I. It's what I wish for every person in this world. One great friendship that stands the test of time. Everyone deserves that.