an actual sock of any material or color that is used by a guy to shoot hot cum into when jacking off. the sock is placed over the hard dick and is worn during the entire act of jacking off as to collect cum and clean the dick when done.
I gave my boyfriend a cum sock to wear on his dick while I watch him jack off.
A man's sock, usually of the athletic variety, used to catch and collect semen. Boys normally use cumsocks to clean up after ejaculation. Also used...a cumrag. Cumsocks are generally easier to hide as crusty remnants can be easily mistaken for any other substance. Usually used to hide masturbatory behaviors from moms who do the laundry.
I couldn't find my cumsock, so I ejaculated on my chest and cleaned it up with an old t-shirt instead.