spoil (one) rotten

spoil (one) rotten

To cause one to expect to receive everything they want by always giving it to them. In this phrase, "rotten" is an intensifier. I think some grandparents believe it's their duty to spoil their grandchildren rotten.
See also: rotten, spoil

spoiled rotten

Fig. indulged in; greatly spoiled. This kid is spoiled rotten! I was spoiled rotten when I was a child, so I'm used to this kind of wasteful luxury.
See also: rotten, spoil