To keel over

from The Collaborative International Dictionary of English v.0.48

Keel \Keel\, v. i. [imp. & p. p. {Keeled}; p. pr. & vb. n.
   {Keeling}.]
   1. To traverse with a keel; to navigate.
      [1913 Webster]

   2. To turn up the keel; to show the bottom.
      [1913 Webster]

   {To keel over}, to upset; to capsize. [Colloq.]
      [1913 Webster]