The horn alarm sounds, “GENERAL QUARTERS, GENERAL QUARTERS, ALL HANDS MAN YOUR BATTLE STATIONS! Forward and up to starboard, down and aft to port. Set material condition ‘Zebra’ throughout the ship.”
Sailors not on duty will drop everything and report to their duty station on the double. This means roll out of their racks, leave their meal uneaten on a table in the mess, or reporting to your station half naked with your clothes under your arm because you were in the shower when the alarm sounded. In this case, it was just a drill one of dozens the crew will experience on its cruise.
The extra detail about forward, up, starboard and down, aft, port, refers to the direction of travel by the scrambling crew. If your battle station is up two decks and forward of where you are when the alarm sounds you take the starboard(right) side ladders. If it’s down and aft(rearward) you take the Port(left) side ladder. This assures that everyone is only going one way on that ladder to prevent traffic jams and likely injuries. This might not be a big deal on a frigate with a crew of 250 officers and ratings, but it sure is on an aircraft carrier with 6,000 sailors aboard. One of the most common injuries aboard a ship at sea is people falling down the ladders which are made of steel and so is the deck. You move at a sort of half-run, limited by the speed of the sailor in front of you as you try to avoid bashing your head or shins on the relatively small hatch openings.
Set Condition Zebra is about the material posture of the ship with respect to its watertight integrity. Condition Zebra locks down the ship like a prison. All watertight doors are shut and the crew cannot open them for any reason, not to go eat or use the head. Opening any hatch closed under Condition Zebra requires the permission of an officer or senior NCO in charge of the compartment or passageway that hatch is in, it also gets logged and is guarded to assure it is immediately closed again. In this condition, the ship is preparing for fire or flooding and it’s taken very seriously. You can be brought up on charges for breaking Condition Zebra without permission. On large ships like aircraft carriers, armed guards(Marines) will be posted on the bridge.