a abriviation or um....... sperm cells but simplified into a 3 letter word for the current generation
dude1: yo dude uh... have u ever jacked it off but accidently spill Cum? Dude2: yo? dude1: never mind...
Cum: a word to describe the mayo you find at the bottom of your older brothers sock draw
Person 1: hey can I have some cum on my burger.
Person 2: sure baby cakes ;)
Bro, read an nsfw fan fiction, it'll give you all the info ya need