The glob of cum that tends to land on the top of your index finger while ejaculating during masturbation.
Dude, i had the biggest cum ring on my finger today after i blew my load jacking off to midget porn
by KrazyKU October 18, 2008
When you ejaculate and a stream of cum flows down all four of your fingers while your hand is on your dick. Therefore giving off the appearance of of having rings of cum.
"Man I ejaculated so hard I got cum rings!"
by Technomancer<3 May 31, 2015