Bay seniors with an unabashed fondness for disco music especially if it’s accompanied by dancers in short shorts on roller skates are advised to check out Kennedy Drive and 6th Avenue in Golden Gate Park any Sunday from 1 to 5. This Roller Disco Party is orchestrated by a mobile DJ unit. Free. And of course you know about the Lindy dancing happening at the same time up the road near the deYoung. What’s next – polkas in the Panhandle?