I’d never heard it called this until today, but the Cupertino effect is:

…the tendency of a spellchecker to suggest inappropriate words to replace misspelled words and words not in its dictionary

This article has some great examples, my personal favourites of which have to be:

Ron Paul, Mike Huckabee, and Sam Brownback occasionally were transformed into Rot Paul, Mike Hoecake, and Sam Blowback, names more appropriate for movie stars in various genres.