Foreword: This is one of the oldest known modifications I know, I first heard of it when I was only 6 years old (over 10 years ago!). The most common way, was the old Stomp & light, but I found some risks with that method. Usually with the stomp & light it would work fine, but sometimes powder would come out and cover the fuse, so when lit, it would go off almost instantly. This method is much safer, because the fuse is protected. NOTE: recently there has been a redesign in some whistle fireworks (not in all places) where there has been more clay added to thwart this modification. This can be overcome, but takes more time, because the clay must be removed. Personally, I would rather make Red Bangers, but they tend to take more time & effort.
Step1: Tape the top and bottom with duct tape.
Step2: Pinch the tube, so you crush up the whistle powder inside. You can feel the powder crushing up.
Step3: Wrap the entire thing with duct tape.
Explodes with an impressive bang. Nuff said.
(sorry no pic)