A special maneuver known only by ninjas, Chuck Norris, Captain Falcon, and Jesus. This meme originated from the popular (albeit overrated) anime "Naruto," in an episode where the character named Gai performs a flying side-kick into the antagonist's face, during which he - in typical anime fashion - screams out the name of his attack: Dynamic Entry.
To perform a dynamic entry, one must come out of absolutely nowhere into a given situation and spontaneously kick one or more persons' asses. The attack may or may not contain massive amounts of gar (the polar opposite of gay), but a dynamic entry - especially in real life - always generates extreme lulz.
Josiah: Josh, get the door, someone's knocking.
Josh: *opens front door*
Doug: DYNAMIC ENTRY!!!1 *actually manages to kick Josh's ass*
Josiah: Hey, asshole, you're late by like half an hour. Where the f#ck where you?
Doug: Beating off.