⚡ Rush flags the whole tab. The kitchen card gets a red band, jumps to the front of every station's rail, and the ticket prints with * RUSH * across the top. The link reads ⚡ Rushed once it is on, and the table's tile carries ⚡ RUSH on the floor.
Use it for a table that has been waiting, or a guest who has to leave. It does not change the order; it changes the queue.
Related: Send, and what the kitchen sees