Men: What would you do if your wife wanted to be a surrogate?

I was watching an old episode of Friends today, and it's the one where Phoebe's brother and his fiancee want her to carry their baby (Babies) for them, and it got me wondering.. what would Phoebe's significant other say if she had one in the episode?

I know there are some women out there who volunteer as surrogates, and in fact, there was a very funny movie called Baby Mama about the topic recently released, but I had to wonder how the husbands (or alternately, the girlfriends/wives, since I know some surrogates are lesbians) felt. So if your wife or girlfriend decided to become a surrogate, how would you feel?