As the name says, this script removes the annoying login requests from Instagram, Facebook, YouTube (mobile only, for the desktop version, try Youtube - dismiss sign in), Reddit, Twitter, Quora, Ask.fm, VK and Pinterest.
Notes for
Quora: if you want to login while the script is enabled, just go to the main page (quora.com) and login from there.
Youtube: this script works only for mobile Youtube interface; for the desktop version, try Youtube - dismiss sign in
Instagram: If you try to open an Instagram profile page (es: instagram.com/mozilla), and you get redirected to the login page (instagram.com/accounts/login/), this script can't do anything, as this means that your IP has been blocked by Instagram, unless you sign in. You can try a different connection or you can try to refresh your IP from the modem/router's settings. If this fails, you can still use https://imginn.com, a site that can show any public Instagram profile without logging in and without unnecessary IP restrictions.
More notes:
Facebook Marketplace: it requires the users to be registered to access. It's not just begging you to login, it's forcing you. No login no access: this script can't do anything for it.
Instagram: they recently introduced an annoying login wall that replaces the third image in a carousel with a login request (only on mobile interface). I currently have no idea, nor will, to find a workaround for it, but if you need to see that blocked image from your phone, just set your browser to Desktop Mode and you wull see the picture as usual.