Classic one-liner...

My friend was working as a waitress in a Lakeside hotel and one couple were having a hell of a time with their young kids who, it was obvious to all, were really playing up to the audience and having the time of their life embarrassing their parents with their table manners, loudness and showing-off. The mother must have kicked her daughter under the table (after half an hour of hell) as the child screamed, "WHY?! WHY DID YOU JUST KICK ME THEN?!" - the poor woman's attempt at diffusing the situation by non-confrontational, sensationalist means (after the dead-eye tactic backfired with a "MUMMY, ARE YOUR EYES ALRIGHT?" quip) were quashed and my friend (who was serving them at the time) said the woman sat up and said, "OK I've had e-bleedin-nuff of this - this stops NOW", followed by a sound slap to the top of the oik's thigh.
A German woman at the next table immediately threw down her knife and fork in disgust and said sternly, "Madam, this behaviour is terrible. In Germany we do not slap our children!".... and here is the one-liner ... the other's woman's husband stood up and said, "And in Britain we don't gas Jews, so why don't you mind your own business!?".

Classic!!!!