The two part act of sucking semen out of the anus with a straw while maintaining enough of a vacuum to get the greasy, and sometimes chunky duckbutter that runs along the taint.
Being careful not to miss a drop, and priding himself as a pro at Felching For Duckbutter, Gabe Athouse aimed his straw and inhaled every last drop of the load he left as well as the grimy, nutsack buildup.
Bromochlorofluoromethane can take on both R and S configurations, depending upon whether the Bromine, Chlorine, and Flourine increase in atomic number clockwise or counterclockwise around the central carbon; the Hydrogen is at the duckbutt.
For long (?), when a guy's got a boner, the tip of it gets wet on it's own with a fluid that is not cum, but has been known to impregnate as it can contain traces of semenosioflous (aka semen). This fluid is sometimes called pre-cum.