Aphrase which, if used correctly, can be a highly amusing insult. Often used as a come back but can sometimes just be used for the sake of it. It is not a good idea to use it on one of your siblings though as can back fire very easily.
E.G 1
Teacher: John tell me a vital condition needed for successful fractional distillation.
E.G 2
John: Hey, Jack!
Jack: What!
John: Your mom!
Jack: What the fuck!
John: Your mom.
Jack: Fuck You John: Fuck your mom
Jack: Leave me alone
John: Only if you leave your mom alone
Etc...