蠢蠢欲动
[chŭn chŭn yù dòng]
Lit. 'creeping restlessly and wantonly.' Idiomatically it means feeling an urge, usually for something unwise or impulsive - similar to saying that someone has the itching impulse to do things. It is sometimes used as self-deprecatingly to say that one is being silly or acting recklessly.