Here is a rebus I thought of again. Can you solve it?
NOT FOR US; multiple Us
NOT FOR USE; another use of Us
Not for use under 6? As would be printed on a medicine bottle
Not for use?
Not for you. (NOT 4 U).
One to you, three not for you
I think the answer is:
Not for internal use
If we call the bottom row "four internal u's", the red mark makes it "not four internal u's", which sounds like the above phrase.
This is also a very common warning printed on product packaging.
I am convinced that the solution contains something similar to the phrase "Not for use in/under (blank)."
There is naught for you at the bottom of the pyramid.