IDIOMS

yak shaving

(idiomatic) A less useful activity done consciously or unconsciously to procrastinate about a larger but more useful task.

Example:   I was doing a bit of yak shaving this morning, and it looks like it might have paid off.
  I looked at a reference manual for my car just to answer one question, but I spent the whole afternoon with my nose buried in it, just yak shaving, and got no work done on the car itself.