My name is Jennis. It's James and Dennis squished together and pronouned like "tennis" but with a "J." At least 90% of the people I meet end up calling me Jennifer, then Jenny, then Jen.
I don't really get asked the "Gin" question, but some idiots do occasionally ask me, "Why didn't your parents just name you Jennifer?" The best response that I can't say back of course is "Why didn't your parents stop before you were conceived?"