1.If your lucky enough to stumble upon a friends moms red thong pick it up.
2.Hide it behind your back and call friend over.
3.Once in range throw red thong at friends face.
4.Upon impact begin laughing as you have just completed the fabled Red Sling.
Josh: "what ma..*hit in face with red thong*"
Zack: "hahah Red Sling beeeyyyoootttcchhhhh!!"
Josh: "Your fuckin weird man.."
Zack: "I'm not the one sniffin my mom's underwear haha"