So why does this duck quack when flourescent light is switched off then?

[Shearer]

@AncientHumanoid

Does it ECHO then !?!?!?

Now then, now then

[Jesta]

@Fridgemagnet

or keep the duck in a metal box.

May I suggest the garage?

[Musicat]

@Crazyhorse

The bigger mystery is why the OP has taken the trouble to install a motion sensing duck under the table by his sofa only to search for a way to disable it, (as opposed to just not having it or taking the batteries out) but fortunately they aren’t asking for an answer…

I’d say they are just ducking the question.

[Richard_Pearse]

@Thudlow_Boink

Why a duck?

Because one of its legs is both the same.

[Senegoid]

The OP, at least, knows the sound of one duck quacking.

[Bryan_Ekers]

@Fridgemagnet

It sounds like Dunmurry’s duck is being triggered by the big electromagnetic spike produced when the fluorescent light is switched off.

Was going to be my suggestion, too. I’ve got a fluorescent light that when switched on or off makes my flat screen TV cycle flicker, and they’re not even on the same circuit.

[Princhester]

@Aspidistra

But now that you have, don’t you really really want one?

No.

[Corner_Case]

@kayaker

I’ve heard about the biscuits/crisps nonsense they’re always going on about, but what’s with the ducks then?

So, saying “then” at the end of a sentence is a British Bobby thing, a Canadian English thing, and a Western Pennsylvania thing; got it.

I hope the duck is cousin to the Talking Big Mouth Bass (ebay) and not the Exploding Penguin (youtube).

[Atamasama]

I think the duck is calling for help.

I missed the word “plastic” on my first read of the OP and I was horrified.

[Dewey_Finn]

It’s the latest thing in the UK; guard ducks.