have cake and eat it too
have (one's) cake and eat it (too)
To have or do two things that one desires that are normally contradictory or impossible to have or do simultaneously. Because "have" can also mean "eat," this expression may seem redundant. However, it is based on the meaning of "have" as "to possess," i.e., to maintain possession of one's cake while still eating it, an obvious impossibility. You're never going to save enough money to buy a house if you keep buying expensive appliances and cars. You can't have your cake and eat it, too. Too many people want to have their cake and eat it, demanding all sorts of social benefits from the government but being unwilling to pay any taxes to fund them.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
have one's cake and eat it tooand eat one's cake and have it too
Cliché to have in one's possession something and be able to use or exploit it; to have it both ways. (Usually stated in the negative.) Tom wants to have his cake and eat it too. It can't be done. Don't buy a car if you want to walk and stay healthy. You can't eat your cake and have it too.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.