Creative Camoflage

Deep inside I'm grinning
but I keep a frown in case
the evil powers are eyeing
the look upon my face.

Happiness writes white?
I'm off in blue, green and red;
in foot-wide waxy crayon
on the prison wall instead.

In a minor tone I'm singing
but in the chambers of my head:
there's a straight eight a-brewing
that'll knock the critics dead.

It's unseemly to be happy - in a poem doubley so -
keep your whistle in a locker and your grin tied down low.