A powerful pose one maintains after achieving something worth showing off to the entire world. A representation of ones badassness. Most commonly seen used on social media with a hashtag preceding the word.
I justkilled that speech. Now, I shall maintain my #boomstance!
When a man inserts his hard penis in a woman's vagina for sex and urinates in her vaginal cavity then immediately switch to 69 position so the male can drink his own urine straight from her pussy while enjoying some oral sex.
She wanted me to piss in her pussy but that lemonade boomerang was a dirty trick.