I'm assuming that ぐちゅぐちゅぺー is an mouth rinsing onomatopoeia because the closest i found was ぐちゃぐちゃ(chewing/squelching)
ぐちゅぐちゅ is onomatopoeia for sloshing liquid around and the ぺー is for spitting it out. It basically is a onomatopoeic and kiddie way of referring to rinsing your mouth.
Hee, is that so? Hey Rumia-chann, it's Listerine*Individual interpretationAbsurdlyHold this in your mouth for 30 seconds and move it around!!Remember it's for your own good!Nnn!It prevents tooth decay*300 seconds left!Is that soIt's for your own good!
