piroma

"Pulled It Right Out (of) My Ass" -- Describes a number or statistic that either you made up on the spot (presumably based on experience) or can't be bothered to make a careful study of to determine a more accurate value.

We were running out of time to finish the estimate and certain vendors weren't getting back to us, so we put some PIROMA prices in a few spots and we'll cover the difference with change orders.