The funny thing is that it's not even a stretch. "://" can easily be read as an emphasised version of ":/" because repetition was (is?) sometimes used for stron

The funny thing is that it's not even a stretch. "://" can easily be read as an emphasised version of ":/" because repetition was (is?) sometimes used for strong emphasis in traditional emotes (e.g. :))), :(((, >>:( etc). So "://" is basically "extremely meh".