  Berry curvature and skew-scattering play central roles in determining both
the linear and nonlinear anomalous Hall effects. Yet in {\it PT}-symmetric
antiferromagnetic metals, Hall effects from either intrinsic Berry curvature
mediated anomalous velocity or the conventional skew-scattering process
individually vanish. Here we reveal an unexpected nonlinear Hall effect that
relies on both Berry curvature and skew-scattering working in cooperation. This
anomalous skew-scattering nonlinear Hall effect (ASN) is {\it PT}-even and
dominates the low-frequency nonlinear Hall effect for {\it PT}-symmetric
antiferromagnetic metals. Surprisingly, we find that in addition to its Hall
response, ASN produces helicity dependent photocurrents, in contrast to other
known {\it PT}-even nonlinearities in metals which are helicity blind. This
characteristic enables to isolate ASN and establishes new photocurrent tools to
interrogate the antiferromagnetic order of {\it PT}-symmetric metals.
