What is the reference being made by saying "I did this at a serious seminar once"? In Osananajimi wa Daitouryou, there is a comedy scene between the main character, Hondo Jun'ichirou, and Ell. The conversation goes like this:

Ell: A small test. It is a simple CPU inspection. I know.
Ell earnestly nodded, then pulled a mechanical pencil out from her pen case and faced the desk. She then muttered a single sentence.
Ell: Ah, I did this at a serious seminar once.
Jun'ichirou: What are you blurting out all of a sudden!?
Ell: It is a simulation. I heard that your test score will go up if you announce it in this manner.
Jun'ichirou: Where are you getting that information from...?
Ell: From 7ch.

This is a screenshot of the same scene in Japanese for reference purpose:

What is the reference being made when Ell said &quot;I did this at a serious seminar once&quot;?
The 進研ゼミ (Shinkenzemi) is a one of the most famous distance learning service for minors in Japan.

'真剣' and '進研', both read as 'shinken.'

'真剣' meaning "seriousness"

'ゼミ' is short for "seminar."

'進' means "progress/advancement".

'研' means "sharpen/polish/study."

This is a parody that use similar sounding Japanese characters.


  あ、これ進研ゼミでやったことがある 
  
  I did this at the Shinkenzemi once.


Much like McDonald's and MacRonald's in English.