Short for "January tan" which can mean either a winter wind burn/frostbite from extreme cold or a actual subtle tan from an abnormally warm and sunny winter day in January.
Whoa dude, you sure got a nice "Jantan" over the past weekend.
A lesbian little girl who's favourite past-time is stepping on men's testicles. One would prefer not to be labelled a jan_tan. Jan_tan(s) usually roam the internet to play counter-strike
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi