A contraction of 'Banter Vortex' - this would be created when an individual said something particularly un-funny in an otherwise banterous situation, thus sucking in all the banter. To be avoided at all costs.
Fairly self-explanitory; an attempted piece of banter that not only falls dead, but manages to actually REDUCE the amount of banterousness around. If you come across any, you are advised to find a Banter Machine quickly and check the area for the presence of a Bantex
Any piece of chat about Land Rovers
"See that guttering over there, I put that up, did a really good job too"