licking, sucking, biting vagina or asshole for sexual passion.
Felching is when one person cums into the vagina or anus of another person and then the cum is sucked back out again with the mouth. This is a higher risk activity as body fluids are being exchanged and transferred a few times however, it depends who is sucking the cum out (e.g if it is their own cum then the risks may be lower than if it is someone else). Felching could be made safer by using femidoms (see femidom).
It occurs after you have been sticking your babe in the can, you bust your nut in there, back up and then pucker your lips up to her rim and suck out your ranch dressing. (This is also the first step of a very advanced maneuver called the Halmstad Hook).