Custom script.
A boy/girl scene shot from your partner's POV that concludes with you getting fucked missionary style and as he gets ready to cum he pulls out and shoots his load directly into your bellybutton completely filling it up. Afterwards he continues fucking you while you marvel at the cum rippling back and forth in your navel. After a little bit of cumplay you ask for a taste so he takes a spoon and scoops the cum out of your bellybutton and feeds it to you.