得意忘形

得意忘形 [dé yì wàng xíng]

1. ■ get [grow] dizzy with success; become highly conceited; be on cloud nine; elated to the degree of forgetting one's form; go wild with joy; have one's head turned by success; lose all bearings in a moment of pride and satisfaction; puffed up with pride:

他这个人有了一点成绩就得意忘形。 His head is easily turned by even a small achievement.