I learned this expression last week, "Yak shaving
It's when you have to do some trivial tasks before you can accomplish the real task. Here's a good example,
"I want to wax the car today."
"Oops, the hose is still broken from the winter. I'll need to buy a new one at Home Depot."
"But Home Depot is on the other side of the Tappan Zee bridge and getting there without my EZPass is miserable because of the tolls."
"But, wait! I could borrow my neighbor's EZPass..."
"Bob won't lend me his EZPass until I return the mooshi pillow my son borrowed, though."
"And we haven't returned it because some of the stuffing fell out and we need to get some yak hair to restuff it."
And the next thing you know, you're at the zoo, shaving a yak, all so you can wax your car.
from Seth's Blog: Don't Shave That Yak!