When you are an expert in the field of "side chickery". You are the 1 in 100,000 who went from side chick to wifey and believe that it is possible for anyone to achieve. You are the master of the art of being a side chick.
Meghan is sad because her ex is with someone new, her friend Kathleen is a master at sidechick-ology and helps Meghan get her man back.
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.