If you and your significant other goes out with your friend and his/her significant other, and you order a table of 4, how would you be seated?

Maybe the diagram below might better explain:
<font="courier new">
MD | FD
======
======
DF | FD
</text>

MD = Male Dingo, FD = Female Dingo, DF = Dingo's Friend, FD = Friend's Date

If the friend is male (which he is), do I sit across from him or sit diagonally from him? What if it was a female friend?