Bay seniors who have always suspected they were born in the wrong century might want to try out the Middle Ages this weekend. Sunday at the Archery Field in Golden Gate Park you are invited to the Debarchery, the Society for Creative Anachronisms’ annual pre-Renaissance faire. From 10 to 5 these backward looking folk with be indulging in archery tournaments, silly games and poetry and various historic forms of tomfoolery. Potluck lunch. Free admission. You are strongly encouraged to take your lutes and tunics out of storage and dress the part.