I'm not sure where "breaker" comes into it, but "necrobumping" refers to posting in very old threads and bringing them to the top again. It is generally unnecessary; a new topic should be started with a link to the old one.
Very good!
"Combo Breaker, sometimes seen as C-C-C-C-Combo Breaker!, is a phrase usually used on message boards to break a chain of posts. On 4chan, the phrase is used to disrupt a popular pastime known as a Combo, which involves posting a series of partially cropped images to bring out the full picture in a given thread."It's a blend between the two.
+1 Internets if you can name the video game where "Combo Breaker!" originated.