the rainbow dash cum jar is a reddit post that depicts a rainbow dash figurine submerged in a mason jar full of cum. the owner of the jar would frequently update the posts and show the cum that has been added. the jar was later accidentally boiled over a space heater, turning the liquid brown.
When a man ejaculates his semen from a distance into another individual's mouth. The individual receiving the semen is sometimes referred to as "the pot of gold" at the end of the Cum rainbow.
Justin positioned himself 2 meters away from Ryan, and with great precision, managed to ejaculate into Ryan's mouth. Justin had achieved a CumRainbow.
A common phrase on sites such as Derpibooru, e621, Rainbooru and Rule 34 that means wanting to impregnate the character Rainbow Dash from the series My Little Pony Friendship Is Magic.
David: dude, I want to cum inside Rainbow Dash
Chad: fucking loser lmao