This must mean you have reached adult manhood
the way you have perfected the poker face, when you
announced Mom, I did bad at school; I saw a dead-
pan expression of despair in your eyes, mirroring
the lacklustre lines around your father’s mouth, my
spirits sagged – until you pressed the report into
my unwilling hands and I exclaimed This is not bad
at all, quite the contrary! guffaws of laughter rang
out, shining eyes of father and son eclipsing the sun;
you are a perfect Sphinx, my son, the mark of the
cool, detached, grown man – well done!
Margaret Alice
http://www.poemhunter.com/poem/2011-04-13-a-perfect-sphinx/