I don’t get it…where else would an “L” go in Colin? Or am I missing something? 
Thanks for the advice everyone. Glad to see almost universal support for spelling it the right way. 
I think he’s joking about how while Collin can say his name is “Collin with two Ls,” people mistakenly refer to Gregg as “Gregg with two Gs” when it’s actually “Gregg with three Gs.” Greg with two Gs is Greg. If it were Greg with one G it would either have to be Gre or Reg.
For the same reason, I was going to ask the lady named Rachel above if her “that’s Rachel with one ‘a’” ever gets a wrong spelling as a result. It’s an old quiz show trick. On Sale of the Century (or whatever it’s called these days) where they have a “Fast Money” segment with questons that are slightly easier but delivered rapid-fire, one clossic old standby is something like, “How many Ts are there in the word tatter?” They often catch out folks who will answer “two”, being preoccupied with “is it a single or a double consonant?” and forgetting the first letter of the word is also a T. Actually, the words used are usually longer, with more real estate between the letters concerned, but I can’t think of an example off-hand.
I don’t recall ever seeing Collin as a first name. It’s always Colin, with one L. Collins is a common surname, but I predict giving the kid two Ls in his first name will result in a lifetine of his having constantly to correct people when they try to spell it, so much so that he’ll probably end up snapping one day and becoming a mass murderer.
One of the best Peanuts strips ever had Charlie Brown writing to his “pencil pal.” He asks someone whether the word “goggles” has one G or two. The other person says “two.” So he spells it “ggogles.” 
(though, yeah, it really has three)
I couldn’t find that strip online. Darn.
And it occurs to me that ggogles would be a great username.
That’s just what I was thinking. But you could always name him Throatwobbler Mangrove.
One “L”, definitely, although I DO like that nifty suggestion in the post just above.
I think I’m still missing something, though…I get the joke about Greg(g), what I didn’t get was how that principle applies to the name Colin. I said to name him Colin with one L, so he wouldn’t always have to say “Colin with 2 Ls” (the assumption on my part being that most people will spell it with one L by default). Dangerosa said it won’t help, and cites the one G/two G Greg thing as an example. But, there is no other place for an L to go in Colin, other than in the middle, next to the first L. That’s why I didn’t understand it or am not getting the connection.
Silly hijack, but I’m confused! 
Do you spell that with one “o” or two?
If I saw Collin, I’d use the rule of thumb where vowels are pronounced long or short based on whether or not there is a single or double consonant following.
Example: Dinner / Diner
I’d be tempted to pronounce Colin like “Stolen”. I claim the handicap of never having known any Colins or Collins.
I once had a roommate named Rick who thought it would be cool to spell it Ric. He finally gave up in frustration. Oddball name spellings are for the birds.
That tends to be more common if the full name is Riccardo. At least, that’s what I assume when I see “Ric”. One of my best friends has that name, and I’ve seen it plenty of times elsewhere.
I’m talking Bumfuck, Texas. Ric was definitely unheard of.
Some famous examples of oddball spellings I can think of include Mathew Brady and Johns Hopkins. Could just be the parents were poor spellers.
No, usually it turns out right if I say that. Sometimes I just spell it if I see them writing or typing it. The funny thing is that of other Rachels I’ve met, only one or two of them have spelled it Rachael. You’d think mine would be the default spelling in most people’s minds.
That being said, at work if I have the slightest doubt about how to spell a name (hotel reservations) I ask them. I’ve gotten a few oddball spellings thrown my way and I don’t want to assume. Sometimes the default spelling isn’t right. But I promise if I get somebody with my name I will ask her which way she spells it and get it right!
Wait, other people spell “Gregg” with three G’s? I thought my boss was just weird!
Thanks again for all the responses, though we’re still no closer to an agreement here.
While we’re on the subject, what do you all think of the name Collier? Pronounced call-yer I guess. That one looks weird to write, but it’s kinda cool. Or is it? :dubious:
Kinda cool for a surname, perhaps. As a given name? Not so much. Not a fan of that trend.
Colin with one L would be far better.
Why would you want to name your son “coal carrier” or “barge”? (See the definitions here on Dictionary.com.) 
I’m sorry. I’m a bit traditional when it comes to names, and that one strikes me as truly awful. Then again, where I live, coal miner is a profession and I do see barges carrying coal on our rivers all the time. Admittedly, they may not technically be colliers.
Slacker, I understand if your wife is trying to be creative or different, but trust me. I grew up creative and different, and it isn’t all it’s cracked up to be. Do you have any idea why your wife doesn’t want a more ordinary name?
I think it’s a surname. Might I suggest Churchill, Baker or Schwarzenegger as an alternative?
Qcawllynne
The only Collin I’ve known was a girl. A one-L Colin will join the illustrious ranks of Colins Powell, Firth and Farrell.