Subterraneous

[Jessica]

Being or lying under the surface of the earth;
situated within the earth, or under ground; as, subterranean springs; a
subterraneous passage.

[Mark Zuckerberg]

Anybody can be [Subterraneous]. No credit [checks], no applications, no membership [fees]… If You support Hip Hop, You are Subterraneous.-OMA

[Tina]

Existing, occurring, or done under the earth