...(obviously not if they genuinely do) ... as people say this all the time when really they just have a cold and feel a bit pants. Their 'flu' (aka a common cold) is normally gone in a few days max whereas flu proper lasts a good 1-2 weeks, comes with fever, full body aches, vomiting, inability literally to get out of bed, and all sorts of other ailments along the way.
I just wish people would hold off pronouncing themselves as having the flu and keep that for when they really do have it. I know, I know, it's not a great deal in the grand scheme, but it's bugging me as have heard it from several different people in the last few weeks (one of whom is in hospital undergoing long-term care and it was the clinical care team who said it, which was immensely worrying given person's current overall medical status, but then actually it wasn't flu, it was just a cold and person was OK again after a few days, thankfully, but way to scare the crap out of all the family telling us they had flu).
For goodness sake people, more often than not it's just a crappy cold.
(With apologies to anyone who actually is currently or recently really laid up with actual flu - you have my sympathies and well wishes). For those of you with a snotty congested common cold, get a grip - but also get well soon ;)