Friend of mine: Sorry I missed the picnic today, I was feeling a bit sick.

Me: Oh? A touch of a cold or flu?

F: no, it's covid

M: how do you know it's covid and not a cold?

F: I just know, I had it before.

M: Oh, sorry to hear that. Maybe you should get the vaccine.

F: I did, three times.

M: Oh. I don't remember the last time I had a cold or the flu, must be 35 years or more, when I was a kid.

F: That's because you never got the vaccine. You should get it.