  We report on a c-axis polarized optical measurement on a
Ba$_{0.67}$K$_{0.33}$Fe$_2$As$_2$ single crystal. We find that the c-axis
optical response is significantly different from that of high-T$_c$ cuprates.
The experiments reveal an anisotropic three-dimensional optical response with
the absence of the Josephson plasma edge in R($\omega$) in the superconducting
state. Furthermore, different from the ab-plane optical response, a large
residual quasiparticle population down to $T\sim\frac{1}{5}T_c$ was observed in
the c-axis polarized reflectance measurement. We elaborate that there exist
nodes for the superconducting gap in regions of the 3D Fermi surface that
contribute dominantly to the c-axis optical conductivity.
