Some say they want the best of both worlds.  Others want their cake and eat it too.  It's interesting how we can adopt unrealistic expectations, yet never fulfill them. 

I've got good news.  I know of a circumstance where you can have it both ways. It occurs during a negotiation when your opponent makes a proposal -- a quite reasonable proposal.  You realize you're close to a settlement, but don't want to be too eager.  You'd like to say "I'll take it!" and also communicate "That's just not good enough."  How can you possibly accomplish both?

It's is possible when you add a third party commonly referred to the 'higher authority'. 

To put it in terms of an example:
 A vendor gives you a price on painting your house.  You've had other bids from $2,000 to $5,000.  You think all are too high because your neighbor had their (similar) house done for $1800 two years ago.  The fellow who's currently giving you a quote has come highly recommended and you're hoping his price is as good as his reputation.  He completes his measuring, crunches a few numbers and says, "I can do it for $1850." 
You'd like to jump on the deal but wonder if you could do better.  You stare at his written quote, glance at the house,  scratch your head and give a pained look.  Then comes the 'higher authority' technique.  You say, "You know what?  This sounds fair to me.  My dilemma is that my wife said we'd have to get the job done within our budget of $1700."

Who knows how the bargaining will come out, but one thing for sure, you're perfectly position to endorse his price yet have a valid reason to ask him to better it.  You can be his friend, yet be demanding.  The higher authority here is the wife, but other have used other family members, their attorney, their accountant and even their priest.

Good negotiators routinely maintain that higher authority that gives them the best of both worlds.