An Artwork is considered a Seiyuu / Voice Actor Joke IF
1. Features two different characters voiced by the same person in one picture.
example: Nozomu Itoshiki and Araragi Koyomi
2. Features a character (one or more) doing a trademark action or saying a memorable quote of another character he's sharing a voice actor with.
example: "I am a Shiva Motorist to the core." - Snow Villiers
3. A character cosplaying as or holding a trademark item of a character they share their voice actor with.
example: Figma EX-001 Konata Izumi as Haruhi Suzumiya.
4. A character is right beside a picture of his or her voice actor(s).
example: Ben Tennyson kneeling down on either Yuri Lowenthal or Tara Strong.
5. A voice actor is drawn on the same way as a character he / she is voicing.
example: Rie Kugimiya drawn on the style of Zero no Tsukaima with that irresistible Tsundere blush a la Louise.
6. A picture of a voice actor doing the antics of his/her character or cosplaying as that.
example: Reuben Langdon cosplaying as Dante.
7. A character appearing as a cameo on a show where his or her voice actor is voicing the main/prominent character.
example: Jean (Queen's Blade Spiral Chaos) appearing in Cameo on Harumi Fujiyoshi's screen in Zan! Sayonara Zetsbou Sensei (yes, we have that deviation here).
AND Lastly, the Golden Rule ~
Seiyuu Jokes only count on OFFICIAL DUBS. Sorry but we don't cater Fandubs here.