Second Cousins? Double Cousins? Or?

Or first cousins, once-removed? I was happy to run into my cousin, Ron Travis (above on the right) yesterday. I hadn't seen him in ages. Even though we only chatted a few minutes, it was nice to catch up a bit. He was with his step-son, Trevor McMahon, and when he introduced me as his cousin, he said, "First cousin? Second cousin?" I said, "Or first cousin, once-removed?" Then we decided, "Who cares? We're related."
The definition of cousin in kinship terminology is that you have an ancestor in common. First cousins have the same grandparents. Second cousins have the same great-grandparents. With Ron, our great grandparents on our Mothers' side were Rufus and Kate Ridnour.
This picture of Ron and his family was taken at Mom & Dad's during the Ridnour cousins reunion in 1957. In back are Mom's first cousin, Esther (Haley) Travis and her husband, Lloyd. Middle row are their children, Shirley, Jenice, Russ and Ron. The little girl in front of Shirley is one of Calvin & Delores Haley's five girls - Kathy, I believe.
As I mentioned a few days ago, Mom and her sisters were always close to their Haley cousins - remaining so as they grew up and had families of their own. Lloyd and Esther lived about four miles from us and attended the same church. We often went to their home or they came to ours. The adults played cards while we played hide and seek, tag or kick the can.
I still am unclear about how cousins are defined - other than first cousins who are the children of siblings. I used to think Esther and I would be second cousins and Ron and I third cousins. But I think it is that Esther (Mom's first cousin) and I are first cousins once-removed and Ron and I are second cousins.
It is more confusing for me to figure out further down the line. The father of one of my classmates and my grandmother were first cousins. So even though J and I are the same age, we are not of the same generation.  His dad and my mother would be first cousins, once-removed? His dad and I would be first cousins, twice-removed? He and I would be first cousins, thrice-removed??? This is where you just need to say, "We're distant cousins."
Then there are double cousins. That happens when two siblings from one family reproduce with two siblings from another family. I remember first hearing the term as a child when Mom tried to explain the double cousins in the Mauderly-Ridnour's. A brother and sister of Grandma Kate Mauderly's married a sister and brother of Grandpa Rufus Ridnour's.
There were no divorces in my parent's generation, so we didn't have to deal with the questions of step-cousins or half cousins. However, after Ron's first marriage ended, he married a second cousin of mine on my Dad's side whose first marriage had also ended. So, when they married, did they become my double second cousins? I'm confused.
I have my own definition of cousin. It is someone I know I am related to somehow that I'm willing to admit being related to.

Oh, yeah, and what are kissin' cousins??