what with one thing and another idiom informal
因为事情一个接着一个，因为忙得不可开交
You say what with one thing and another when you want to explain that the reason you have failed to do something is because you have been very busy.
What with one thing and another, I forgot to call you yesterday. 由于昨天事情一件接着一件，我忘了给你打电话。