On a more serious note, one of the main issues surrounding gay marriage is a matter of semantics. Some people define marriage as strictly the union of a man and woman. Others interpret a broader meaning.
At first, this seems trivial, why not just broaden your interpretation? If a homosexual couple says: "We're married" then marriage has a broader meaning. The same word can be used in other scenarios as in the example from webster: "seafood marries with other flavors". So why restrict the usage of the legal world?
Well, there does have to be a legal definition somewhere. Otherwise, if the legal word and dictionary word were the same people could go around marrying inanimate objects and whatnot. So marriage does have to be defined somewhere in our legal framework and does need to specify who can marry whom.
So to appease those with a strict marriage definition legislatures created a sort of euphemism: "civil union". But if we have marriages and civil unions and both have the same legal consequences, what legal difference is there between them? The only difference I see is a label. And that label allows government official to discriminate. If both unions have the same legal purpose then they should be the same thing and labeled the same. Either we call unions between people marriages or civil unions.