A small band of online consumer advocates is attempting to turn this Friday the 13th into a nightmare for exhibitors and movie studios. The activist group, calling itself WeCanDoThis.com, is spreading its message via e-mail and its Web site pleading that consumers not see a movie Friday in order to protest the high price of tickets. It’s calling the effort the National Ticket Picket. WeCanDoThis.com expected its site to be up and running by Tuesday; its online home has been at IdeaTown.com. “”Thousands and thousands visited the site in the past 24 hours,”” said spokesman Mark Jonathan Davis, and hundreds of e-mails were sent asking that recipients pass the word along to boycott movies Friday.