Closet O' Zombies
Back when 3e first came out, I was DMing the game. The PCs had arrived at a ransacked gnome stronghold. As they searched through the fortress, they realized they saw plenty of blood and signs of a struggle throughout but no bodies.
Their search continued until they opened a "closet" door, and inside was a heap of gnome corpses that had been transformed into zombies.
Since zombies only got one action per turn, the little buggars took forever to exit the "closet," giving the PCs ample to time to mow each one down.
There was much complaint about how so many creatures could fit inside a "closet."
First off, it wasn't a closet, but a pantry, which, while very closet-like, isn't the size of a typical closet.
Secondly, they argued that it should only hold three or four zombies at most since there wasn't enough "space" according to the rules of how creatures are spaced on the game map.
I said "no way" (and still argue the point today) because in my opinion, zombies don't need living space or have "personal space" that we as living humans appreciate. Zombies will happily stack themselves like cordwood if a necromancer tells them to do so, and they'll just sit there and wait until something piques their interest.
Anyway, the amusing scene unfolded of the PCs lining up -- two on each side and one in front -- as the zombies made their death march into our whirling weapons.
Since then, the players always have a good chuckle whenever we open a closet door in a game (warning one another of the potential of a "Closet O'Zombies") or face seemingly overwhelming odds that are quickly dispatched (saying "Looks like another Closet O'Zombies!").
"Focus all your firepower on that Super Star Destroyer"
Taking a line from "Return of the Jedi," this is an in-game code for our characters to always attack the biggest creature first, and that everyone should always attack the same creature and not worry about the peons.
While we as players know the source of this code, our characters certainly don't, but its just the running-gag statement our characters use to initiate usage of this particular tactic.