Zippy's Mouth
A vaginal opening that, on first look, seems slim and tidy - a second glance, however, reveals that it needs additional fastenings for it to remain closed.
Well I got my first glance at Sandra's nunny last night. I wish I'd kept it as a first glance, as the more i looked the more I realised it was a Zippy's Mouth. I could've done with a second pair of hands to close it back up.