  We demonstrate that multiple-Higgs production at the LHC is the most
sensitive probe of first and second-generation quark flavor in the Higgs
sector. In models where new scalars couple to light quarks, gigantic di-Higgs
and even sizable tri-Higgs production rates can be obtained, which can be used
to either discover or severely constrain such theories. As an example, we show
that the most stringent bounds on enhanced interactions of the
$125\,\textrm{GeV}$ Higgs to the down quark in extended Higgs sectors are
obtained by looking for the extra Higgs bosons that provide for such
enhancements using the di-Higgs and $Zh$ topologies. In this context, we set
new limits on the 125 GeV Higgs coupling to the down quark as strong as
$\lambda_{hd\bar{d}} \lesssim 30 \lambda_{hd\bar{d}}^{\textrm{SM}}$ -- a
dramatic improvement over previously available bounds. Regarding
second-generation quark flavor, we obtain new limits in the coupling to strange
as strong as $\lambda_{hs\bar{s}} \lesssim 10
\lambda_{hs\bar{s}}^{\textrm{SM}}$. In addition, we show that the currently
unexplored triple-Higgs production topology could be a potential discovery
channel of a wide variety of extended Higgs sectors at the LHC, including not
only models where extra Higgses couple to light quarks, but also popular
theories where they have preferential couplings to the the top.
