“For Heaven’s sake.”
Or, if you want to get more personal, “For Pete’s sake.” Or a reasonable facsimile thereof.
Each of these expressions is a plea for goodness, begging the receiver of the message to look past the motives behind his or her actions and to act according to that which is ultimately right in the universe.
“For Heaven’s sake, don’t be so stupid!”
“Make up your mind, for Pete’s sake!”
Whether you find the expression effective or not is up to you. But please, if you do choose to include it in your arsenal of communication tools, don’t be among the people who say:
“For Heaven’s sakes.”
Even worse is the homonymous “For Heaven sakes.”
1. Purpose; motive: a quarrel only for the sake of argument.
2. Advantage; good: for the sake of his health.
3. Personal benefit or interest; welfare: for her own sake.
Firstly, pluralizing the possessed sake (as in “For Heaven’s sakes”) is unnecessary, and arguably incorrect.
Secondly, using the possessor (Heaven) as an adjective to describe the plural sakes (as in “For Heaven sakes”) is so wrong it almost doesn’t even warrant further explanation. Just don’t do it.
This is yet another example of an expression that, if used incorrectly often enough by enough misled people, can somehow find its way into the realm of that which is acceptable in conventional English.
Please, stop the madness. For Heaven’s sake.