expression, godan verb (-ru)
get carried away; be full of oneself; become conceited
Describes someone who becomes overconfident or self-satisfied, often due to a small success or praise. Used critically of others or oneself.
ちょっと褒められただけで、彼はいい気になっている。
Just because he got a little praise, he's getting carried away.
いい
Don't get full of yourself. It's only just begun.