To be honest and upright even in private; literally, to have nothing to be ashamed of even in the darkest corner of one's room.

to behave with integrity even when unobserved; to have a clear conscience even in the privacy of one's own room

The roof is leaking and it happens to rain all night; describes a situation where bad luck or problems occur one after another.

when it rains, it pours; used to describe a situation where one misfortune follows another in quick succession