Sliding into the front of the line says your time matters and everyone behind you is extras.

Cutting is a small announcement about rank. It says your afternoon is the main event and the people ahead of you are scenery, which is almost never what you actually believe, and yet the act says it anyway. Most of the time it comes from running late and hoping nobody minds. Everybody minds; they simply say nothing.

When you are in a hurry, take the wait anyway and spend the minutes on something dull. If you genuinely need to go first, ask out loud and let the person decide. Asking changes the whole transaction.