Amazon has great deals on pepper spray! Check out the reviews on this lovely item:
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Top review:

Whenever I need to breezily inflict discipline on unruly citizens, I know I can trust Defense Technology 56895 MK-9 Stream, 1.3% Red Band/1.3% Blue Band Pepper Spray to get the job done! The power of reason is no match for Defense Technology’s superior repression power. When I reach for my can of Defense Technology 56895 MK-9 Stream, 1.3% Red Band/1.3% Blue Band Pepper Spray, I know that even the mighty First Amendment doesn’t stand a chance against its many scovil units of civil rights suppression.

When I feel threatened by students, no matter how unarmed, peaceful and seated they may be, I know that Defense Technology 56895 MK-9 Stream, 1.3% Red Band/1.3% Blue Band Pepper Spray has got my back as I casually spray away at point blank range.

It really is the Cadillac of citizen repression technology.