  Long-distance contributions of operators of the effective non-leptonic weak
Hamiltonian containing charmed currents have been recently studied.
Penguin-like contractions of these operators, denoted as charming penguins,
have been shown to be relevant for several B decays into two pseudoscalar
mesons. In particular, they are expected to give large enhancements to
processes which would be otherwise Cabibbo suppressed. Their contributions
easily lead to values of BR(B^+ \to K^0 \pi^+) and BR(B_d \to K^+ \pi^-) of
about 1 \times 10^{-5}, as recently found by the CLEO collaboration. In this
paper, we show that such large branching fractions cannot be obtained without
charming penguins. This holds true irrespectively of the model used to compute
the non-leptonic amplitudes and of the relevant parameters of the CKM mixing
matrix. We use the experimental measurements of the B^+ \to K^0 \pi^+ and B_d
\to K^+ \pi^- decay rates to constrain the charming-penguin amplitudes and to
predict BRs for a large set of other two-body decay channels where their
contributions are also important. These include several pseudoscalar-vector and
vector-vector channels, such as B \to \rho K and B \to \rho K^*, which have not
been measured yet.
