Some Transformers toys have had the ability to produce showers of sparks, simulating weapons or hot exhaust.
These sparks are produced by a mechanism that, when activated, allows a spinning steel wheel to rub against a flint, similar to that contained in a cigarette lighter.
Sparking mechanisms are notorious for wearing out after prolonged play, and for littering a toy's surface with burned-in crunchy bits, giving the spark-exit area a black-peppered appearance.
Though this gimmick is cool and fun, it isn't one that Hasbro considers any more for use in toys, after a similar gimmick in Barbie dolls drew national attention for setting children's underwear on fire.