An insult used by those who have a minimal vocabulary*. Usually in an attempt to upset or hurt the person who dared to insult this person by trying to undermine their mother. Never followed by anything. For example - Your
mum smells etc...
It is related to another insult in this wonderful array of
words.
Ya Mam.
This insult is gramatically incorect showing that the persons incoherency is shocking by using this insult. Futhermore, Ya is not a word.
Overall, Your
Mum is a Pointless insult. Used by chavs for chavs.
* In this case, minimal vocabulary means
words like food,
beer & usually swear words.