A term born from the anime 'Nichijou'. It is the combination of 'gun' and 'tsundere' to make 'gundere'. It is the same as tsundere but the cold-like treatment towards the love victim is taken to a new level, incorporating the use of weapons ranging from sub-machine guns to heavy artillery.
The cold-treatment in 'tsundere' is usually just verbal, where as in 'gundere' the cold-treatment is extreme violence via heavy weaponry.
Female (blushing): I-It's not like I'm doing this for you or anything.
Male: I don't really need your help..
Female (extreme blushing): *Fires rocket launcher at the male* I'm going to help you anyway! be grateful!
An issue that men frequently have. Gunderplunk is when your testicles become stuck to the side of your leg. Frequently occurs when wearing boxers for a whole day of hard laborin the sun.