Yet another example of a 'strong verb' past form. It is the past tense and past participle of misspell. Apart from dialectal preferences, it is equal in meaning to the form misspell in all ways.
British English shows a preference for retaining strong verb forms (burnt, learnt, spelt, dreamt, spoilt etc). American English shows a preference for ignora... I'mmean simplification (burned, learned etc).
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.