We all know iOS devices can't support Flash, but how much is just the restrictions placed on the OS? Is it possible to install it with a jailbroken device?
The short answer is no. However, Flash was available for JailBroken iOS devices under a tweak called Frash, but it's long since been outdated, forgotten, and abandoned, plus it doesn't work on iOS5. It used to only play videos, and games would hardly run (or make it crash). So yes, it was possible, for it has been done before, but you cannot at the moment. Adobe's discontinuation of support for the ARM Flash Player will retard further development of Frash even more than it already has been.