I always wondered how you got sixth cousins twice removed or whatever. You get my drift. :) So I looked it up on trusty google and this is what I found.
(1st cousins share the same grandparents, 2nd cousins the same great-grandparents, and so on. In my opinion, by the time you get to 6th cousins, you're probably pretty much related to everyone. I don't even think most people could name their 5xgreat-grandparents.
The tricky part is the # removed part. I think I'm explaining this right. The children of your cousin (1st, 2nd, doesn't matter) are once removed, and the grandchildren are twice removed, and so on. But usually you don't say that your first cousin's children are your first cousins once removed. They are commonly referred to as second cousins (or probably even more commonly these days, your cousin's kids LOL).
So if you and a cousin share the same great-great-grandparents, you are 3rd cousins. And if you are invited to that same cousin's grandchild's Christening, that child is your 3rd cousin twice removed. And since that is a pretty tenuous familial tie, you can probably be pretty cheap about the gift. Get 'em some onsies or a sippy cup.
An easy way to think of it is: Your first cousin's kids are your first cousins once removed. Your first cousin's grandkids are your first cousins twice removed. Your kids and your cousin's kids are second cousins to each other. Your grandkids and your cousin's grandkids will be third cousins! Now if you want to get into second cousins once removed, you probably don't know them anyway!)
I don't know if all of this is true. I would love to here any different things you have heard!