The ones about not being able to get out of bed if there was a £50 note on the floor and talk of “real flu”.
Flu can be asymptomatic, mild, moderate or severe. It’s still “real flu” regardless of severity.
It’s a tiresome and potentially dangerous myth that it always has to be severe. And no you might not know for definite that you have flu unless you test for it/are tested but you don’t have to be confined to your bed to have flu.
https://www.cedars-sinai.org/newsroom/yahoo-life-why-does-the-flu-make-some-people-sick-but-not-others