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.
When someone you have had sex with in the past shows up or are friends with someone you want to have sex with in the future, they are a poontangboomerang.
"Dude! I went to a party with my new girl , and her skank friend showed up that I was down and dirty with the night before! That girl is a poontang boomerang !"