Another name for a larger than average Vagina, see also wizards sleeve
Christ! i went down on this bird last week and it was like looking straight into the mouth of a yawning hippo
by cheesey February 13, 2004
a simile for a particularly large vagina, named so because it resembles a hippo yawning. minus the big teeth a hippo possesses of course. that would just be weird.

a hippo's yawn can usually be found attached to a slosher or perhaps a lady that has given birth to twins with heads like south park's mr mackey.
trevor : how'd it go with that slag last night then?
pete : mate, she had a minge like a hippo's yawn
trevor : that bad huh?
pete : seriously, it was like stirring a bucket of wallpaper paste with a pencil
by MrCasual January 6, 2011
A phrase used to describe someone's huge vagina.
''how was Linda in bed then?'' ''I didn't even touch the side's her fanny's like a Hippo Yawning''.
by NicLauren'sole January 6, 2016
A girl with a vagina so badly damaged when she upens her legs it looks like a hippo with its mouth open.
Dude I was going down on her and took her panties off and I got scard I thought I was on the Discovery channel, She had a cunt like a Hippo yawning and it made a wierd noise at me.
by MERT July 1, 2012