A lesser-known variant of the phrase "a pretty penny" (i.e. very expensive).
That Aesop moisturizer cost me a penny and a half!
A costume or cosplay that is not completed or incomplete because you accidentally left part of the costume back home.
Where's your cosplay? It's a half-play right now, I left the wig at home so I have to go buy another.
When your having a threesome and one girl is giving you head but doesn't finish you off and leaves it to the second girl to finish you .
I had a threesome yesterday and the girl half a jobbed me