  We introduce two ansatzs for the 3-form potential of Euclidean 11d
supergravity on skew-whiffed AdS_4 X S^7 background which results in two scalar
modes with m^2=-2 on AdS_4. Being conformally coupled with a quartic
interaction it is possible to find the exact solutions of the scalar equation
on this background. These modes turn out to be invariant under SU(4) subgroup
of SO(8) isometry group, whereas there are no corresponding SU(4) singlet BPS
operators of dimensions one or two on the boundary ABJM theory. Noticing the
interchange of 8_s and 8_c representations under skew-whiffing in the bulk, we
propose the theory of anti-membranes should similarly be obtained from ABJM
theory by swapping these representations. In particular, this enables us to
identify the dual boundary operators of the two scalar modes. We deform the
boundary theory by the dual operators and examine the fermionic field equations
and compare the solutions of the deformed theory with those of the bulk.
