I Haven't (cleaned the garage, done the laundry, etc.)
The first, crucial step in getting out of this kind of oversight (or laziness, as the case may be), is not to try to indicate token ways in which you contributed to the job at hand. Equally ineffective is to make vague mention that you know you did something, but can't remember for sure.
Perhaps an example would be appropriate here. Say a loved one has asked you to vacuum the house; of course, you haven't done that because you're a very busy person, and also someone with deep-rooted psychological issues that prevent that kind of goal-driven, productive activity. It would not be effective, upon the return of the other party, to point out that you've taken the vacuum-cleaner out of the closet. This kind of incremental step will not be of interest. Also ineffective would be to act, in general terms, like you have already vacuumed--this will eventually backfire, perhaps badly. And acting as though you are unsure whether you have completed the vacuuming is absurd on its face, unless you have sustained a closed-head injury. You may find yourself sustaining just this kind of injury if you do such a poor job of lying.
Intended, of course, for entertainment purposes
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