Do you wanna go halves on a bastard?

exp.

Heard in Waterford

One of the most despicable chat up lines that man ever invented... It is basically suggesting to a member of the opposite sex that you wish to copulate with them but do not wish to take part as a legal guardian of any offspring that might be produced from the activity.

In use

Hey yungwan, ja wanna go halves on a bastard ya big slapper?

Posh English

Hello young lady, would you care to engage in amorous congress without either of us assuming legal guardianship of any resulting progeny, you promiscuous wench?