the act of firing a noob tube at close range so it doesn't detonate but becomes lodged in the target. It's like using a shotgun, but instead of firing many pellets, it fires just one big "slug". Usually results in a kill. Popular among COD noob tubers who go to the extent of taking the "Ouch" challenge a little too far. However, this seems to be less "noob-ish" because slug tubers do not take advantage of the huge AOE explosion resulting from long-range tubing which may get a double/triple kill. Some people think that it's more humiliating to be slug tubed rather than be knifed.
Xen: damn! I got slug tubed! Why can't you use your knife instead??!!
SluG_Diu-ber: because slug tubing is so much more fun!