A: You made me wait for well over half an hour at the restaurant. What was the matter?

B: I bumped into an old classmate on my way, and we caught up a bit. Sorry I lost track of time.

A: That excuse simply won’t wash with me.

Note: This idiom means “not to be accepted or believed.” It originally alluded to a fabric that would not stand up to washing but by the late 1800s was used figuratively for other kinds of failure.