一时兴起----by fits and snatches

例句:
A:It's impulsive of you to do these things.
你做这些事太冲动了。
B:It's my style. Actually,I do anything by fits and snatches.
那是我的风格。事实上，我做任何事皆凭一时兴起。

同义词:
by fits and starts