helping oneself; arranging to suit oneself
Often used for serving oneself food or taking liberties in arranging things without asking. Can imply self-serving behavior.
At the drinking party, please help yourself to the food.
His plan was self-serving; he didn't listen to others' opinions.
Compound of 手 (hand) and 盛り (serving, piling up), literally 'hand-serving'. The exact historical derivation is uncertain, but it likely originated from the idea of serving oneself with one's own hands.