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1.
That awkward moment that occurs when a group of guys and a girl are talking and the topic of conversation turns to girls and their pros and cons, male health issues or other topics best kept among men. Someone then realises that there is, in fact, a female present. An embarrased silence then follows. This is a Hermione Moment.

It is named after the many scenes in the Harry Potter series when Harry and Ron forget that their friend Hermione is actually a girl.
Steve: Man, Jessica has a nice pair of...
<Dave elbows Steve hard in the ribs>
Steve: er.. Hi Teresa! Um, what do you think of Jessica's... er...
Dave: Dude, Hermione Moment!
by George McBob April 21, 2009