sinfest_download.rb

#!/usr/bin/ruby

require 'date'

start = Date.parse("2000-01-17")

(start..Date.today).each do |id|
        url = "https://sinfest.xyz/btphp/comics/#{id.to_s}.gif"
        puts url
        system("wget #{url} -q")
end

For your information, a recent update to the sinfest website changed the base url to http://www.sinfest.net/btphp/comics/

Thank you