I'm not intersex, but I'm posting here anyway, if you all don't mind.
Anyway, more or less, I have a phantom penis (in fact, there's an entire topic about it in the FtM transsexuals section). I used to feel it more often, lately, however, it only happens a few times a week or so. I'm not sure why. Anyway, my phantom penis can feel hard and what not, but then I look and there's nothing. And yes, I would compare it to feeling like you pissed yourself and then seeing that there's nothing there.
Gender euphoria, on the other hand, no. I consider it more of gender dysphoria because the moment I realize it's not physically there, it causes dysphoria.