Who are those people with shark teeth in GTO? In GTO, some character faces transform into weird/creepy faces.


In episode 35, when Onizuka attend a wedding and fakes to be the groom, he ask the bride if it doesn't bother her. She and her whole family makes this strange shark face :


 


In episode 40, when a little girl that we know in love of someone, comes and knock at Yoshikawa's and Uehara's door (during the Okinawa's trip):




What is the signification on this transformation? Who are those people with shark teeth?
The girl of the episode 40

The girl of the second episode is Kumiko Fukada. 

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The reason why she does have shark teeth is because Fukada is written 鱶田and 鱶 means "(large) shark", therefore the author is making a pun (Source)



Even thought she only appear this time in the anime, she is more present in the manga :

In both the anime and the manga, there is an episode where  Murai receives a letter from a girl which the name start by the letter F. The girl playing the mediator, Kujirakawa Fuyumi, is in fact the one who sent him the letter, while Murai is attracted by another girl. 

In the anime, this girl is named Aoi Fukada while in the manga this girl is Akane Fujita.




At the left, Aoi Fukada. At the right, Akane Fujita

At the end of the chapter, in the manga, we find out that Murai has been confounding Aoi Fukada and Kumiko Fukada. Because Aio is not named that way in the anime, there was no such pun, therefore we never saw this part of the story animated.

The presence of this girl in the 40th episode may only be a reference of the manga.



The girl in the episode 35

As long as this wedding does not happend in the manga, we can only presume, but as she really looks like Kumiko Fukada so we can guess that this is the same girl. 

The pun is the same as for Kumiko : because everybody is Fukada's family is named Fukada, everybody has the same shark teeth as Kumiko as if the name caused this family trait to be hereditary