Like "come" is? That seems like the obvious answer to this query...
I write you not in your capacity as advice columnist, but as America's Sexual Neologist-In-Chief.
Here's a list of words: blood, sweat, tears, come (or semen, or jizz, or, if you must, cum), precome. Bile, pus, piss, snot. Human bodily secretions have short, common names. There's one glaring exception: vaginal lubrication. Two words, seven syllables, all suck. There's not a simple clinical term, there's not a slang term, all there is is circumlocutions and euphemisms. "Girlcum" won't do—it's too easily confused with female ejaculate, which is a completely different fluid. We need a word, Dan, badly. One or two syllables, easy to say. I propose "zude," derived from transudate, but I wouldn't dare dictate. It's your language—we just speak it.
On the other hand... the female state of arousal should not be confused with the male orgasm. The male orgasm is the exclamation point at the end of the act for him (and his pre-ejaculate would be the analogous fluid). The female state of arousal is both a process and a plateau. A girl gets wet as she becomes aroused; she remains wet (with any luck) during the act(s). I suppose it's possible that my concern for the verb form of "wet" in this context—"I'm wetting!"—is yet more evidence of my pernicious and previously noted male-centric default response to questions involving women's genitalia and sexual response cycles. So perhaps I should recuse myself.
Any better ideas than "wet," Sloggers?