the natural arguement about reproduction has nothing to do w/ a hetero couple being infertile. It has to do the the parts fitting together. Try plugging one electrical cord into another. Obviously it doesnt work because it was "designed" to fit into an outlet.

Hold on - nothing was "designed"! Male and female parts fit very well together but unless you think that some supreme being decided to create them this way (and Christianity, for example, may cause you to believe this) then you have to accept that no matter how well they do a job there's no design involved.

Most male fish ejaculate into the water - there are no parts fitting into other parts there. By your argument, they too are against nature.

Evolution is a very efficient, but purely mechanical, system via which physical functions develop - there's no possible way you can say there's intent behind it. Bode, you don't have an argument.