Red doesn't typically talk like this, but she's kind of caught up in the moment. And her anatomy is...questionable. She's capable of mimicking the sensation of a vagina/cervix/uterus, but they don't serve any function other than being erogenous zones and vanish when she doesn't need them.
She's also addressing Allen as a mortal like it's a thing, but it's not really. Red isn't immortal so much as timeless; she's a fey creature that existed long before Allen found her and will continue to exist long after, provided she doesn't die in the meantime.
