left hand man
A guy who will cockblock an entire friendship group of males from impressing a female by making some stupid comment, so she looses respect for the other males as she thinks their all going to be like that.
All the guys thought hey this girl is good fun we've got banter.

The left hand man started to meticulously pick apart all the random sweeping statements, turning the event into a boring moan at the female not giving enough facts in the pub on a friday night!