Emoticons/emojis created by layering several text characters on top of eachother (overstriking). These instructions are from 1976, and might have been around as early as 1972.

This technique was possible on the amazing 1970s PLATO computer, and probably never again after that? You could also move the text-chars around on a pixel level. Pictures/info from platopeople.com.

How were these things done? Well, on PLATO, you could press SHIFT-space to move your cursor back one space — and then if you typed another character, it would appear on top of the existing character. And if you wanted to get real fancy, you could use the MICRO and SUB and SUPER keys on a PLATO keyboard to move up and down one pixel or more — in effect providing a HUGE array of possible emoticon characters.