I believe that George is commenting on something that most of us realized early on in our lives..... No matter what, a Man always pays for sex. Whether it's with money, food, gifts, emotional attachment, etc.... very few women give up their intimate attentions without first being properly compensated for their time and involvement.
True, even for a one night stand you got to pay for a few drinks at least.
I think its sad that no women has ever bought you a drink before sex.
Its happened but I bought us a few more after.