The only real comeback to ya mum that isn't whining about how infantile your insulter is. We can only assume what is meant by 'this'.
Scenario 1-boring, slightly civilised
Tony: What are you doing tonight?
Gordon: ya mum!
Tony: Now do we really have to resort to this childishness?
Gordon: Does ya mum have to resort to childishness?
Scenario 2- Childish, good
Tony: What are you doing tonight?
Gordon: ya mum!
Tony: keep my mum out of this and I'll keep this out of ya mum
Gordon: Yes, master.
by kung-fu jesus October 30, 2004
"If I wanted some cum back I'd get it off your mom's chin"
"Keep my mum out of this and I'll keep out of your mum!"
Note: Using this retort still means you're getting owned
by ihumpmarinesforbreakfast July 01, 2005