With apologies to R. L. Stevenson, Patrick Brontë, Longfellow, and people who like scansion or have good taste:
Under the spreading chestnut tree,
Dig my loo and let me be.
Glad do I poo and gladly pee,
and I wipe my ass with a will.
This be the stall's fresh-writ graffiti:
"Here he sits where he longed to be,
Having eaten too much chili con carne,
He quenches the fiery arrows."
An alternate first line for the second quatrain is "This be graffito in the WC".