Flame Thrower
Rudy Blanston was mad. The flame thrower he ordered had all sorts of defects. The on-off buttons were switched. The design had the shape and color of a toy he had bought for his kids. There was a hole in the housing that allowed the flaming liquid to leak down his leg. And even when it was off, it emitted a sound that attracted bats.
Blanston could only get a store credit, so he ordered some hand grenades. But the grenades turned out to be nothing more than water balloons with fragmentation lines drawn on.