Out of the loop

Seriously, what’s the significance of the word? There are many teens in my neighborhood, as well as me having a teenage sister, who laugh hysterically at the word.

Some people will respond with “Wanna know what else is massive?” Is this a sex joke or something?

[I live in the US now but grew up where many people did not speak English so I may not understand jokes that well even if my parents are English speakers.]

Edit: Looks like it’s from someone called Ninja. https://knowyourmeme.com/memes/ninjas-massive-you-know-what-else-is-massive