to get from sb/sth all the money, help, information, etc. they have, usually giving nothing in return
MILK / SUCK SB/STH DRY
Meaning of MILK / SUCK SB/STH DRY in English
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005