Nuttin' Button
The term I like to use for the prostate and/or G spot.
"Yeah Stacy, I gave him a little push on the ole nuttin' button."
Button-Nuttin
The act of laying a penis flat on the owners own body and aiming the tip towards his belly button, then proceeding to use either a massager or water jet head to massage the penis to orgasm, therein delivering a load into the belly button.
C-Bass had a fear of Belly Button play until he learned about Button-Nuttin, now after some practice he loves it :)