When writing a comment, users will frequently add a postscript prepended by a forward slash (/). Just as people can get carried away with PS, PPS, PPPS, etc., so can users go crazy with their slash-notes.
Sometimes the phrase "slashies" is itself used as a postscript to indicate the user if aware of their going overboard.
Wow, Hillary Clinton's hot. I'd hit that like the fist of an angry god.This is a corruption of the older internet meme of closing a fake HTML tag after a block of text, e.g. </pedantry>
///okay, not at all
/at least we're fairly confident it is