go fifty-fifty
To split something evenly between both parties. I promised the kids that I would go fifty-fifty with the last cookie. Because you helped me so much with the yard sale, I want to go fifty-fifty with the profits.
go fifty-fifty
(on something) to divide the cost of something in half with someone. Todd and Jean decided to go fifty-fifty on dinner. The two brothers went fifty-fifty on a replacement for the broken lamp.