Common reproach to children. The character 挑 is read tiāo here (third tone 挑战 'to challenge' is a different reading). Compare 偏食 (piānshí), which leans toward 'partial-eating' = preferring some foods over others, often used in nutrition contexts.
memory
挑 'to pick / select' + 食 'food' — to pick at your food. The same 挑 as in 挑选 (to choose).
