Abstract: During the Chandra campaign to extend the CDF-S from 4Ms to 7Ms, a fast X-ray transient was discovered. The wealth of ancillary data, plus subsequent optical/NIR limits, put interesting constraints on its origin, effectively ruling out a Galactic transient, as well as all known SNe and the vast majority of GRBs and TDEs. The remaining possibilities include a low-luminosity / orphan short-duration GRB and a highly beamed TDE involving an intermediate-mass black hole and a WD. However, neither explains all of the observed properties. No similar event is seen in the Chandra Source Catalog, suggesting event rates comparable to those expected from orphan GRBs or modestly beamed TDEs.