As per my Knowledge you have the concept of this dialogue wrong. From what i know this term as ‘ghori’ is used for a woman who sleeps around i.e. wherever she finds grass or whatever to eat.. wahan hi moonh maarti hai .. hence the term .. lagaam do.
I know this cos an incident occured a few years back where i was a witness ..where a few women started fighting and with men too ..and my uncle knew their background..and he intervened to stop the fighting ..and ofcorse he too was angry at the whole thing and in anger he was calling those women ‘ghoriyan’ and to do lagaam of their tongues. didnt know what it meant at the time. later asked my cousin sister ..what was you dad saying to those women .. and she told me what their background was … that they slept around ..jahan kuch milta hai wahan hi moonh maarti hain..hence the term of ghori..
but i like TLKs version too .. MQM walay hain hi aisay 