There’s nothing worse than when your dog actually did eat your homework, but you're still not believed.
Unless of course you’ve tested positive for opiates and your alibi is that you ate some bread rolls.
This is the claim of a 58-year-old pipe fitter, suspended from work for 11 weeks after testing positive for morphine - an extract from the opium produced by poppies.
Speaking to the Liverpool Echo, the father of two, who wishes to remain anonymous, insists the test reading was the result of him eating poppy seed bread and buns the day before the test.
After receiving the positive results, the Liverpudlian paid £120 for a private hair-follicle test, which came back negative, and obtained a letter from his GP stating he had never been on any prescribed medication, such as morphine or painkillers - which contain opium.
“I am a married dad and have two grown-up children. I have never taken drugs,” said the Liverpool man.
“I thought to myself ‘I have something in my body that I have no idea where it has come from’ - it was very worrying.”
The pipe fitter’s online research led him to an experiment on BBC One’s Rip Off Britain: Food, which aired in May. Over three days, 72-year-old presenter Angela Ripon ate a loaf of poppy seed bread and a poppy seed bagel to see if a drug test would pick up opiates. The results showed the presence of morphine.
The construction worker added, “I knew straight away that it had to be the poppy seeds I had eaten and I actually thought 'Great that explains it.'”
His company have since taken him back, although the contractor that he failed the test for has refused to accept his return to work.
So, can eating poppy seeds really lead you to fail a drug test?
“If you eat a poppy seed roll, it could give rise to a positive result on a urine drug test for morphine,” says Atholl Johnston, Professor of Pharmacology at Queen Mary University.
While the morphine content of poppy seeds can vary by a factor of nearly 600, drug tests are highly sensitive, and could return a positive result even after a relatively small number of the seeds.
However, Professor Johnston makes it clear that eating poppy seeds will not get you high any time soon.
“It is unlikely that a single poppy seed roll, or even a dozen rolls, would result in an individual ingesting enough morphine to have a pharmacological effect.”
Nevertheless, it’s advisable to wait up to three days after eating poppy seed products before taking a drug test.
And in case you’re wondering what other kinds of foods could lead you to fail a substance test, we’ve got the answer for you: the best kinds.
Like pizza and pastries.
Now a fair number of people would probably testify that pizza is effectively an addictive drug anyway.
But according to a breathalyser manufacturer, food products that use yeast can in fact make you fail a breathalyser test. This is because yeast makes dough rise by fermenting sugars into a number of substances, one of which is alcohol.
And if you’re unlucky enough to be breathalysed immediately after eating pizza, then this could cause you to fail the test.
According to the same source, this also applies to ripe fruit and fruit drinks. These can ferment and produce just enough alcohol for you to test positive.
Thankfully, because the alcohol is in your mouth rather than in your digestive system, you should be fine after about 15 minutes. Alternatively, you can rinse your mouth out with water.
Then there’s hemp seeds (often found in granola bars), hemp seed oil and hemp seed milk.
And even poor, innocent, tonic water can help you to fail a drug test.
Tonic water was originally drunk for its quinine, an antimalarial drug derived from the bark of the South American cinchona tree.
This led to the invention of gin and tonics by a British official in 19th-century colonial India, who found a way to liven up the anti-malarial prescription.
But having a few G&Ts could also liven up your drug test results.
Quinine is sometimes used to cut illegal drugs like heroin, and the amount of quinine present in your drinks can return urine test results that mirror those of drug users.
So you could actually end up failing both a breathalyser and a drug scan. Which would give you one heck of a hangover.