Unlike in the US, the earthed plug has in France an additional hole and the socket has a prong. In Germany tgere is no prong in the socket, but two side contacts at the top and bottom of the socket. The plug is the same for germany and France. Unlike in the US you can use an earthed plug in unearthed sockets in France and Germany without any adapter.

Tin foil, as said previpusly, is a bad, and potentialy dangerous solution. In Europe, most fairly recent sockets have kid protection shutter that block the holes in the socket. They unlock when you plug in the plug as both prongs apply similar force on the shutters at the same time. This shutter will most probably rip the tin foil from the prongs. It can be dangerous if there is some tin foil that remain inside the socket, and even worse if it partialy sticls out.
in foil is a dangerous.
In my experience, I only had the following issues in Europe:
- the whole socket was loose (partialy hanging from the wall)
- US camera charger without cord was a hanging a bit loose from the EU-US adapter (the adapter was fitting well in the socket).

And as for bending prongs, its easyli done with unearthed ones (partialy on plastic), but good luck with the 4.8mm earthed ones!