I've heard some crazy stuff over the years, while monitoring Concorde departures from LHR, though mostly from other BA aircraft.
But the following....
The BA155 (to Cairo), a 777 that had 260 pax, called the tower, he had to return to stand as a 'pax had a ******** in her hand luggage, (* denotes what we could not quite understand).
Neither were the tower sure what the BA Capt had said, so they asked to repeat, two more times, we were still not sure either.
Not because the Capt was incoherent, it's just that no one could quite get their heads around what they thought he had said. I certainty could not.
So the Capt said he'd spell it out, after the Tower told him that 'they were having trouble with one of his words'.
So he did, "Sierra, Quebec, Uniform, India, Romeo, Romeo, Echo, Lima".
The incredulous tower asked for clarification, "a squirrel?"
The Capt confirmed yes, the pax had a live squirrel in her hand luggage.
It turned out that she had two of them.
She must have had them on her person before boarding, surely two small mammal skeletons, probably moving, would have been picked up as her hand luggage was x-rayed.
Eventually it left late, minus one pax and two live, small, furry mammals.