In Japanese media, using “gomu” instead of the English loanword “condom” (コンドーム) is deliberately childish or euphemistic. It appears in:
Put it all together:
The line “Gomu wo tsukete to, iimashita yo ne” is spoken by in the anime series “Bakemonogatari” (episode 8, regarding the “Monkey’s Paw” arc). However, the most famous delivery comes from Hitagi Senjougahara in a later episode of the Monogatari series (specifically Nisemonogatari or Tsukimonogatari depending on the adaptation timing). In Japanese media, using “gomu” instead of the