Beef.
It is an operation which Okabe made up to soothe Mayuri's worries about him not looking good, after they went and bought everything needed to prepare & throw a party for Part-time Warrior. Or perhaps the operation refers to the shopping for food.
(The Organization's intervention raised the prices on the market!!) Thus he requests more funding.
Namesake[]
In Norse mythology, Audhumbla (or Auðumbla) is a primeval cow.