on the downlow

1 秘密

private secret underground confidential covert clandestine stealthy ulterior backstreet underhand surreptitious hush-hush cloak-and-dagger hole-and-corner backstage inwardly crypto- confidence secrecy on the side behind the scenes in secret behind closed doors on the sly under the counter in camera

2 秘密地

backstage inwardly on the side behind the scenes in secret behind closed doors on the sly under the counter in camera

3 暗中

underground covert sneaking backstairs under-the-counter in secret