ASCII art n. The fine art of drawing diagrams using the ASCII character set (mainly `|', `-', `/', `\', and `+'). Also known as `character graphics' or `ASCII graphics'; see also boxology. Here is a serious example: 

         o----)||(--+--|<----+   +---------o + D O
           L  )||(  |        |   |             C U
         A I  )||(  +-->|-+  |   +-\/\/-+--o -   T
         C N  )||(        |  |   |      |        P
           E  )||(  +-->|-+--)---+--)|--+-o      U
              )||(  |        |          | GND    T
         o----)||(--+--|<----+----------+     


         A power supply consisting of a full wave rectifier circuit
         feeding a capacitor input filter circuit
Figure 1.

And here are some very silly examples: 

       |\/\/\/|     ____/|              ___    |\_/|    ___
       |      |     \ o.O|   ACK!      /   \_  |` '|  _/   \
       |      |      =(_)=  THPHTH!   /      \/     \/      \
       | (o)(o)        U             /                       \
       C      _)  (__)                \/\/\/\  _____  /\/\/\/
       | ,___|    (oo)                       \/     \/
       |   /       \/-------\         U                  (__)
      /____\        ||     | \    /---V  `v'-            oo )
     /      \       ||---W||  *  * |--|   || |`.         |_/\


                    //-o-\\
             ____---=======---____
         ====___\   /.. ..\   /___====      Klingons rule OK!
       //        ---\__O__/---        \\
       \_\                           /_/
Figure 2.

There is an important subgenre of ASCII art that puns on the standard character names in the fashion of a rebus. 

     +--------------------------------------------------------+
     |      ^^^^^^^^^^^^                                      |
     | ^^^^^^^^^^^            ^^^^^^^^^                       |
     |                 ^^^^^^^^^^^^^            ^^^^^^^^^^^^^ |
     |        ^^^^^^^         B       ^^^^^^^^^               |
     |  ^^^^^^^^^          ^^^            ^^^^^^^^^^^^^^      |
     +--------------------------------------------------------+
                  " A Bee in the Carrot Patch "
Figure 3.

Within humorous ASCII art, there is for some reason an entire flourishing subgenre of pictures of silly cows. Four of these are reproduced in Figure 2; here are three more: 


              (__)              (__)              (__)
              (\/)              ($$)              (**)
       /-------\/        /-------\/        /-------\/
      / | 666 ||        / |=====||        / |     ||
     *  ||----||       *  ||----||       *  ||----||
        ~~    ~~          ~~    ~~          ~~    ~~ 
     Satanic cow    This cow is a Yuppie   Cow in love
Figure 4.