To attack or cut with a switchblade.
To (cause to) make a sudden move or transition.
To spring open or up.
A folding knife with a blade which opens automatically (under spring pressure) when a button is pressed.
To use tear gas.
Any lachrymatory, non-lethal chemical compound that causes the eyes to sting and water and/or irritates the respiratory system, mostly used for controlling crowds during riots or as self-defense.