I was wondering what others have come up with.
Feel free to post your favorites from other authors like Oscar Wilde, etc. but I'd prefer seeing those you yourself have thought of.
For example, a friend wants you to join a fiction book group, but you just don't like reading novels. Don't say, "I'm sorry, I don't have a car on Thursday nights" -- your friend may figure out how to get you a ride, or perhaps offer to switch the group meeting to a different night. In which case, you either end up doing something you don't want or coming off as a jerk for not giving your real reason in the first place.
I haven't looked but I'd imagine they are not so unique and others have come up with similar things before. Personally, I did like this one though:
"The question is the only animal which gives birth to itself."
Spare the rod, spoil the child.
A few of Lacan's,
The Other does not exist.
Desire is the desire of the Other.
We are all mad here.
The universe is the flower of rhetoric.