I pressed it and my screen went dark. If I hold it down my screen like shuts off and I can't turn it back on unless I restart my computer.
Figured it out.
Ctrl+Alt+Down flips the screen to be upside down, Ctrl+Alt+Left/Right rotate the screen counter-clockwise and clockwise respectively. Ctrl+Alt+Up changes the screen back to normal.
This shall be an eventful school week.