Binkan is the main character of the TV-show "Binkan The Sensitive Salaryman" in Bokusatsu Tenshi Dokuro-chan.
Hence the title, Binkan is the most sensitive salesman, if not the most sensitive man ever lived... just the slightest touch or pressure on his body results into an unbearable status of pleasure, rendering him immobile while twitching in combination with desperate moans.
In the Anime The Binkan series is so popular that food products and in season 2 even a movie was made of Binkan. These foods have the uncomfortable side effect of making the person that eats Binkan-labeled foods as sensitive as Binkan himself for a short time.
Dokuro has made Sakura eat Binkan-Sausage by force and surprise throughout the anime.