Ш-87

ПРОТИРАТЬ (ПРОСИЖИВАТЬ) ШТАНЫ highly coll , humor or iron VP subj: human to work or study long hours, usu. very diligently (in refer, to a job - often a clerical one-or other occupation that the speaker considers unworthy of such diligence)

X протирает штаны - X wears out the seat of his pants.

«Сажа валит из труб - это убыток и одновременно напоминание: есть приказ... о ликвидации убытков, над чем мы ежедневно просиживаем штаны» (Дудинцев 1). "If soot pours from a chimney, that is a loss and at the same time a reminder: there is an order...about the reduction of losses and we wear out the seats of our pants day after day trying to achieve this" (1a).