Lactose intolerance.

Remember when there was an epidemic of claims of lactose intolerance? It was such that there was a "Seinfeld" bit about it:

Jerry: I have never seen one episode of "I Love Lucy" in my life ever.

Donna: That's amazing.

Jerry: Thank you.

Donna: Is there anything else about you I should know?

Jerry: Yes, I'm lactose intolerant.

Donna: Really?

Jerry: I have no patience for lactose. And I won't stand for it. Uhm, I'll be right back. (Goes to bathroom)

You don't hear about lactose intolerance anymore, for some reason. Or I don't. Maybe you do.

Merry Christmas!