Muster drill is a contest to see which passengers can eat the most hot dogs with mustard, before the ship sets sail. No just joking.
When you get to you cabin, read the posting usually on the back of the door to tell you your muster station. This is where you would go in case of an emergency. You will have to take your life jacket with you. Do not blow on the whistle. They are not cleaned and you don't know who blew on it before you.
If you don't want to walk to the muster station, take your life jacket and get there early.
There will be a demonstration on the proper way to put on the jacket.
Sometimes they bring you to the life boat and sometimes they don't.
After the drill, the ship sets sail and there is music playing on the Lido Deck. The grill is open now go down those hot dogs with muster