"Gishi gishi" is the creaking of a bed.I get that you've tried to personalize the "an an" part to fit yourself, but,
"Gishi gishi an an" is the 2ch sound effect for hearing your neighbours have sex.Momiji, I know what you're trying to say.Gishi gishi wan wan!Gishi gishi wan wan!Momiji's learned some weird expression.Gishi gishi wan wan!......Wan.