A Wink & the Truth

I was paid to smile, show my teeth for all to see, 
but though I walk a mile, your shoes won't fit for me. 

I was told to laugh—snort, guffaw, with running tears—
and learned to hide my wrath. Now revelation nears.

You asked me for a joke; I had but one to tell. 
Truth is all I spoke, shattering your ancient spell.