To use or spend something and still keep it; have both when you must choose one of two things. Often used in negative sentences.
Необходимость выбрать какой-либо из двух вариантов, часто используется в отрицательных предложениях.
Roger can't make up his mind whether to go to college or get a job. You can't eat your cake and have it too.
Mary wants to buy a beautiful dress she saw at the store, but she also wants to save her birthday money for camp. She wants to eat her cake and have it too.
"You cannot eat your cake and have it too", said my boss when I told him I want to have more holidays and more responsibility at work.
"Один пирог два раза не съешь", сказал мой начальник, когда я рассказал ему, что хочу больше выходных и больше обязанностей на работе.