What does this phrase, from Pynchon's novel Gravity's Rainbow, mean?
Schnorp, his hair blown like holidays of hay…
There are no references to "holidays" or "hay" in the preceding several pages.
It's a very obscure usage. From OED definition #3 for holiday...
Here's a similar instance in a short story by William Saroyan
To my mind, Pynchon is comparing Schnorp's hair to a little pile of fluff/dried grass/hair such as might be found behind the sofa after a perfunctory cleaning. More specifically, perhaps, ungathered straw in a harvested field (that will be swirled into piles by eddies of wind).
Ultimately of course, this usage does derive from the normal sense of "holiday", in that it's a bit left over because someone took a short break while cleaning/painting/tidying up.