i usually tell them i'm a gypo , live in a caravan & only deal in livestock, mainly pigs, dogs, goats.
this covers most aspects of most scam or nuisance calls.
However if you have a young child thts just started talking gibberish, say 'ill just get the person you need to talk to' and give the kid the phone.
my accountant advises to keep a loud whistle handy for the nastier calls.

Kids,tired of being bothered by your pesky parents?
Then leave home, get a job & pay your own bills, while you still know everything.

Go 9nto You Tube and see what happens, they will say you will be arrested and have your accounts frozen yadda yadda...

But if you pay now the courts will let you off.

But payment of non payment of tax is a civil not criminal offence unless you are a tax avoider.

So ignore.

This scum often call my 90yo neighbour who is blind glad to say she still has her marbles and gives them short shrift but how many vulnerable people get scammed.

One more point