Ya mum is commonly used as an irrefutable comeback when properly used. The result is best if it implies
something to do with the insultees mum being
sexually active. Being females the results are funny as we dont REALLY like ya mum.
(Works best when a straight female says it to add
confusion)
e.g
Davo: Hey cockhead.
Bobbio: Your mum likes cockheads.
or
Davo: What were you doing on
the weekend?
Bobbio: I was doing ya mum
doggy style.
or
Davo:
Oh My God! I was so excited.
Bobbio: Ya Mum was excited, when I shagged her!