Simon West and Mark West are the male counterparts of Susan Test and Mary Test. Simon West was voiced by Bill Mondy and Mark West was voiced by James Arnold Taylor. They made their first appearances on the episode Johnny Alternative when Johnny Test and Dukey were sucked into a portal that sent to them into Simon and Mark's world. Simon and Mark's parents might look exactly the same as Susan and Mary's parents because there is a picture in their house that looks exactly like Lila Test.
|"Oh my gosh! , this is bad!" – Dukey|
Simon looks almost exactly like Susan Test but with short hair. His brother Mark also looks nearly exactly the same as Mary Test with short hair.
- Glam-Glam Girl (Eugenia, or the female Bling-Bling Boy) has a huge crush on Simon, just like the way Bling-Bling Boy has a crush on Susan Test.
- It appears that they have coupons for Joni to test stuff for them just like the way how the Test sisters have coupons for Johnny.
- Like the Test sisters, they're scientists and they can invent machines and guns.
- The colors on their shirts switch places with the colors on Susan and Mary's shirts.
- The first time the girls became boys was in Johnny's dream in Rock-a-Bye Johnny.