Possible Clues:

• Shakes or trembles
• Trembles in fright
• Quiet! They have so much milk there it shakes you
• Shakes from milk producers after asking mum
• They'll shake you to keep quiet over where the milk comes from
• How it shakes one to tell 1 down to be quiet
• Trembles violently as from horror
• Shivers violently as from fear
• Trembles violently as with fear
• Be quiet with the milk there, if one is not comfortable