That's the question Carterton's Mike Playford has been asking himself after a mysterious and smelly brown substance landed on his shed from the skies this week.
Mr Playford said he was in the shed of his Hughes Line property at 5.30pmon Tuesday when there was "a big whack and a splatter" on the shed roof.
"I thought it was rain at first but when I went outside it wasn't raining at all.
"Then I started to smell something sh**ty and I saw the big brown splatter on the side and roof of the shed."
He said to avoid contamination he quickly disconnected the shed spouting - as it led to his water supply - before hosing the brown muck off.
"It's definitely come from a great height, because it hasn't come from a vehicle as the road is 250 metres away on one side and 100m away on the other."
Civil Aviation Authority spokeswoman Emma Peel said every year it received claims of supposed airline discharge, normally at this time of the year.
The organisation's website says ducks and geese are generally to blame for the fouling.
"During the nesting incubation period, August to October, the female will sit on her nest for a long period of time. "The accumulated excrement is released when flying some distance from the nest."
The website said it was "virtually impossible" for solid waste to escape from an airliner's toilet system.
Mr Playford said both he and wife Carolyn had scanned the sky for the perpetrator but didn't see a "solitary thing",
"If it was geese it can't have been just one of them - it's a bit of a mystery."
