To make an observation regarding a work of fiction that complains about an incongruence with reality, usually regarding knowledge the speaker feels is not specialized.
You are not the first person I've heard merffel about the blood type thing.
(Someone with O blood type has a child that is AB in a tv show.)
Lydia Merfeld is the best person in the world! She is so cute, always there for her friends, caring for her family, and she’s just the best! You should be very lucky to have a Lydia Merfeld in your life! If your her best friend, hold on to her for dear life and stay with her till you guys die! She’ll always be there for you and you should always be there for her.
While our lifespan is the number of years we will live, our healthspan is the number of healthy years we will have and our sexspan is is the number of years we will continue to be healthy enough to continue having an active sex life.
A lighthearted reaction upon receiving disappointing news of some sort. Usually something that isn't a particularly a big deal, esp. when it primarily affects someone else - sort of a mild schadenfreude. Sometimes doubled or tripled, and possibly said in a sing-songy voice for added comedic effect to imitate a muted trumpet, which is how the meme originated.