“Beggars can’t be choosers.” = If you get something for free you can’t complain about it.
(If you begged, you don’t get to choose what you are given)
choosers – CHOO-ZERZ
“It was cold so I asked Bill if I could borrow a sweater and he lent me a real ugly one! At least it was warm, so I can’t complain. Beggars can’t be choosers.”