When I was dating my wife in college I sneezed and sorta added the "SOOOOUUULLLLL train" scream to my sneeze. She laughed hysterically at the time (30 years later and she hasn't laughed at it since). Now when I sneeze in front of her or my daughters, I'll sometimes just quietly say "train" afterwards. My daughter asked me why and I tried to explain, but she just thought I was a goofy dad. She finally heard the famous intro to the Soul Train TV show just recently, and told me she now gets it, but not that it's funny or anything.