1)top : *guri* *guriri* [*twist* *twist* or maybe *grind* grind*] bottom: *poki* *pokiki* [*crack* or *pop*]
R to L 2) "Yu- there's a sound!" "A Aa["O oh" might be better] it's the sound of the bones in the waist"[waist is the closest word, but I think they use it to mean spine or abdomen] "It seems fun!" "Really?"
3) "Reimu will make the sound too!" "Haha impossible, you don't have bones, right" *guriri* [*twist* or *grind*] *nejiri* [word for *twist* or *wring*, not the sound]
4) "Yu~ I have bones at least!" "Wow.... yeah you definitely don't" *guririri riri...* [*griiiiiind* or *twiiiiiist*]