FIDE Master, Kevin Bachler
The nickname Caveman and the concept of caveman chess was thrust upon Kevin in 1981. At the time he was an Expert, working to become a National Master. Kevin had just finished playing fellow Expert Jack Young at a tournament at the College of Lake County - a college that held a number of chess tournaments in the 1970's through 1990's.
Jack and Kevin were doing a post-mortem analysis, and FIDE Master Albert Chow walked up and was watching. The game was fairly tactical in nature, and Jack and Kevin were both willing to explore ideas that were "off-the beaten path".
After a few minutes of watching, FM Chow shook his head and said to Kevin "You play stone age chess. You play like a caveman!" Of course, Kevin's friends immediately ran with this and the nickname "Caveman" was born.
The nickname was reaffirmed the next year, during the first Midwest Masters tournament. Although not a master, Kevin was invited to the tournament by organizer Helen Warren to have a chance to learn and improve. Ranked 29 out of 30, after four rounds, Kevin had a score of 3-1 with no losses. At that moment he was rated over 2200, and while he knew he would play the last game, had to momentarily consider whether to play the last game.
National Master Chuck Kramer commented "You have to play. YOU'RE the Caveman." Chuck was correct, of course.