When Heidi and I changed our classroom themes to a pirate theme, I wanted a new pirate-themed attention-getter. This is what I settled on.
Teacher: All hands on deck!
Students (while saluting): Aye, Aye, Captain!
The kids were totally gaga for it. It's hands down the best attention-getter I have ever used. I thought they'd tire of it as the year went on but they always loved it. The other 2nd grade classes heard us doing it and when it was my turn to have another class for rotations, I could use the attention-getter and they knew what to do from hearing us do it!
The added bonus of this attention-getter is they have to empty their hands (of scissors, pencil, book, etc.) in order to salute so it really helps them focus their attention on you, and not what they were doing.
All hands on deck!