When surrounded by geeks, you might text or bbm a friend to say you're surrounded by geeks or if you're really daring say it out loud.
Quite ironically it is a play on "I fear the Greeks, even those bearing gifts" from Virgil's Aeneid and one would generally have to be quite clever (or geekish) to know that. A phrase common among public school chaps in England.
geeks: it's really good fun, here, like star wars.
normal person: Ok, right
geeks: (chanting) join us, join us...
other normal person: I fear the geeks!