elf cum Share definition Flag A slang term for eggnog, popularized by Dave Attell. Dude I went to my grandmother's christmas party and drank a gallon of elf cum.I didn't get drunk but I did gain three pounds. elf cum by flem78 November 26, 2013 0 0 Get merch Get the elf cum mug. Buy Now — $32.95 See more merch