I hate

I once said it to a passing sneezing stranger in the street in Rome, he loudly said thank you back and was very english. Britsabroad radar did us both proud that day. #csb

I particularly like saying it to strangers.

What - that they have a 20% chance of dropping dead when Judgement comes?

H5N1
Mate.
Plague is caused by a bacterium.

H5N1 is a virus.

You'll be asking for antibiotics for your cold next.