I have an artist buddy who has 8 of those bubble guns rigged to the roof of his car, all shooting backwards. (Disguised in 2 giant, colorful 'fun missiles') Makes a pretty decent cloud of bubbles. Easily enough to someone drop back. Always hilarious when he goes through an intersection, and everyone has ro stop like 15 seconds to wait for the bubbles to fall before they can go.

I’ve been thinking about a wicked strong spotlight aimed back, if you want to show me your bright lights up close I’ll show you mine