CUO GU ( Translation Please)

Greetings..


A gentleman who I talk to now and again that studies Shuai jiao told me that to help improve my china I need to learn how to Cuo gu....
Can someone translate.. he gave me an example of pulling the shoulder joint out of place while pulling or throwing..

does this mean a skill or a technique can someone help.....
Does this mean to break dislocate or maybe is it to violenlty pull.. Does it have to do with ripping muscle or something...
any help would greatly be appretiated


Victor