I told LL that I had Man Flu this morning.. she says it is just a cold... "three days coming, three days with you and three days going"... WTF is that all about then...? 
Basically correct. Your standard cold lasts for about a week to ten days from first niggle to final snot blowing session.
Man flu lasts about the same, but is subject to much whinging and whining for many months afeter, about just how bad it was.

Influenza, the real thing, lasts for approx 2/3 weeks of pure unadulterated misery, and then about another 2/3 weeks of getting your energy back if you've survived.