Have your cake and eat it, too
If you EAT your cake, you no longer HAVE it... its gone...
Ergo, to wish to have your cake AND eat it, too is, as stated, to want two mutually exclusive things... '
It would be like saying someone wants to save their money and spend it, too.
Straight from the horse's mouth...
When Buying a horse, you do not trust the seller as to the horse's age ... you look in its mouth for the truth of the horse's age and health.
Horse trading also gives us "you don't look a gift horse in the mouth"... in that you shouldn't criticize the quality of a gift.
And also " long in the tooth" how long a horse's teeth appear tells you its age... so a horse with long teeth is very old.
Here's a really obscure one...
to say some one is the "Spittin' Image" of their father or mother...
This actually is a miss-wording of the original phrase... that someone had the "spirit and image" of their parent.