First a quick introduction, since the days when this was a common concern are rapidly fading into history. From the
NES onwards, games consoles included various security measures to prevent gamers playing cartridges bought from other territories. Of course, as whenever content producers put barriers in the way of consumers, a market quickly sprung up for
circumvention devices. The obstacles ranged from the trivial (differently shaped cartridges for different regions as in the
Mega Drive) to the ridiculous (Nintendo's elabourate handshaking scheme, employing a 4 bit microprocessor, that persisted through the 8 and 16-bit eras). These adapters sat between the console and the cartridge, allowing the imported games to be played, and gamers to get their fix a few months early, or unfortunately far too often, play a game that would never see light of day in their country.
A concept invented by Nintendo to scare people away from using adapters and disuade people from buying import games. Their reasons for doing this are discussed elsewhere. They claimed that adapters drew too much power, and would damage your SNES's cart slot. This is false for two reasons, the use of an adapter, even one that require the insertion of a second cartridge, use minimally more power than a cartridge on it's own; and SNESs have an internal fuse that would blow before this would happen. It is true however that adapters allow you to remove cartridges with the SNES switched on, and some are even so badly designed that they let you insert cartridges back to front. Doing so will almost certainly blow the internal fuse, and the latter may also do severe damage to the workings of the game cart and console. If you did blow this fuse, Nintendo used to charge an obscene amount of money replacing it, citing 'adapter damage' as the cause of failure. If you have an RS screwdriver or a set of gamebits, you can replace the fuse yourself. (And put in a 50/60 switch and lockout bypass while you're at it. Errr... wait, that's prolly why you have the gamebits in the first place.) So what I'm saying is that adaptor damage is just a blown fuse. (Unless your 6 year old cousin put Tales of Phantasia backwards into your shitty Hong Kong bridge adapter, and really fuX0red your SNES)