This is when one person bites the back of the neck of another person and proceeds to mount them in that position in a more exaggerated "doggie style"- the way two feral cats would. Some sort of anal fingering or licking must also take place at some point in the sexual encounter because feral cats ofter forage through rubbish. An excess of disturbing cat noises is preferred.
I think my roommate was playing feral cats last night. I kept hearing all kinds of meowing and screeching sounds.