A great, and creepy article on going on a cruise for conspiracy theorists.
Bronwen Dickey, a really good writer for Popular Mechanics, recently went on a cruise called, I kid you not, ConspiraSea. As the subhead reads, "It ended poorly."
http://www.popularmechanics.com/culture/a21919/conspiracy-theory-cruise/
(Bronwen's a woman, btw, a fact not made apparent in the article.)
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I thought everyone knew that!!!! 
who wouldn't go ashore in Mexico because "it's a lawless society." 
"Wonderful to have you with us," the woman said. "We're only now beginning to understand the quantum realm."
... or working on it instead of a dummy like Richard Feynman, eh? 
Math? Let's use our "feelings" instead!
They're going to end up sailing right off the edge of the Earth!
Given what they believe, wouldn't that be a dumb thing to do? 
Like, try squeezing a ball for 10 minutes. Now do it for 6 hours.
But that particular conspiracy theory drives me fucking bonkers.
There are tons of sites, but really the first thing to look at in my mind is the most recent incontrovertible 'evidence' (I put evidence in quotes because it's silly to even have to prove certain positions, like 'dinosaurs existed'), namely that NASA had an orbiter capable of taking high resolution shots of the lunar surface out in that neighborhood a few years ago, and they imaged several of the Apollo landing sites. (Thus debunking one old saw from that conspiracy, namely, "why aren't there any photos of the landing sites"
. Descent stage of the LM, astronaut tracks and lunar rover tire tracks (where applicable) are clearly visible in all of them.
https://www.nasa.gov/mission_pages/LRO/news/apollo-15.html#.V7rfEODr2Uk
Also, for the past 45 years scientists, etc. have been bouncing lasers off of the laser reflectors left by the Apollo astronauts, to precisely measure the Earth-Moon distance. These are not "all people in on the conspiracy", either.
http://physics.ucsd.edu/~tmurphy/apollo/lrrr.html
http://science.nasa.gov/science-news/science-at-nasa/2004/21jul_llr/
Here's how it works: A laser pulse shoots out of a telescope on Earth, crosses the Earth-moon divide, and hits the array. Because the mirrors are "corner-cube reflectors," they send the pulse straight back where it came from. "It's like hitting a ball into the corner of a squash court," explains Alley. Back on Earth, telescopes intercept the returning pulse--"usually just a single photon," he marvels.
The round-trip travel time pinpoints the moon's distance with staggering precision: better than a few centimeters out of 385,000 km, typically.
Targeting the mirrors and catching their faint reflections is a challenge, but astronomers have been doing it for 35 years.
For the "conspiracy" to hold up, NASA would have had to deliver these reflectors to each of the "fake" landing sites. They also, presumably, would be faking the LCROSS images that we got back a few years ago, etc.
Here's probably the biggest go-to site for debunking all these arguments-
http://www.clavius.org/
More:
http://www.ibtimes.co.uk/debunking-myth-that-moon-landing-was-hoax-1457501
https://blogs.nvidia.com/blog/2014/09/18/debunked/
Rationalwiki:
http://rationalwiki.org/wiki/Moon_landing_hoax
("direct evidence" and "photographic evidence" in particular, which expand on some of the points I make above)
...one fun thing about this PARTICULAR conspiracy theory is that unlike ones based upon other past events, the evidence disproving it is not disappearing and getting more clouded by time but rather will only become more and more glaringly un-ignorable over the next couple decades. In fact, it's perfectly preserved. So it's a decidedly losing position your friend has taken, whether he has to face it sooner, or later.
