How much (weight) did you put on (while away on vacation). Как много вы набрали (веса за отпуск)
Explanation: In yesterday's poverty-stricken shtetl, obesity was a rare sign of affluence, and was much envied. When someone returned home to his shtetl after having been away on vacation ("af datsha"), he was likely to be accosted with this question upon his arrival.
(цитата с одного симпатичного сайта)
Во как дело было: нищие жители местечек набирали вес (жирели) на местечковых дачах. Спасибо автору сайта, рассмешил.