Bed Flags???

Hey there guys, ive been seeing more and more prerunners cruising around with giant 4ft-5ft banners waving off their trucks on 5 ft' poles or whips... idk how the hell they manage to mount these and what their using as a pole, and i'm trying to get one. so if any of you guys have an idea how they pull off waving a banner so big without it falling off going 90mph, let me know! thanks.

p.s; would a CB whip perhaps work?

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 08 v8 Titan