Osomatsu-kun S01 E24 Iyami's Body is Full of Germs!

"You're seeing way more than double! Try sextuple!"

Totoko becomes infected with personality-altering bacteria after Iyami sneezes on her, leading Osomatsu and Choromatsu, along with Dekapan, to find out the secret to Iyami's nastiness by taking a "Fantastic Voyage"-style trip inside his body.