Ballad of the Birthday Mapmaker

Tale of a mapmaker who ruins a birthday with endless charts.

Sing, O muses, of banners and cake,
Of a birthday that kingdoms would tremble to make.
The streamers were hung and the candles were lit,
The children arrived, each ready to sit.

The gifts piled high in a shimmering stack,
The clown blew balloons till his cheeks turned to slack.
The piñata was waiting, suspended with pride,
And laughter erupted from every side.

But lo! In the doorway a shadow appeared,
A scholar of maps whom the villagers feared.
His satchel bulged full with compasses three,
With protractors, rulers, and charts of the sea.

He strode to the punch bowl and promptly declared:
“This basin’s a gulf; be cartographically spared!”
He charted the sofa, the table, the floor,
And sketched out the dog as a coastline offshore.

The children, bewildered, abandoned their games,
For each was assigned new geographic names.
The birthday girl wept when she heard the decree:
“Your cake is an island, surrounded by sea.”

The candles were numbered, the frosting surveyed,
The balloons became planets in orbits arrayed.
The clown, once so jolly, was redrawn as a cape,
“An outcropping rock in a mountainous shape.”

The parents despaired as the hours grew late,
Their party consumed by cartographic fate.
And when at long last the guests fled in dismay,
The host could be heard with a moral to say:

“Mark this in your annals, inscribe it most hearty,
Never invite a cartographer to a birthday party.”

Written for:"The Writer's Cramp" 
Prompt: END your story or poem with this line, exactly as it appears below - bolded:

Never invite a cartographer to a birthday party.
Line count: 37