For example, if you were to open a fast food shop and call it Walt Disney's Fries Company, the Walt Disney cartoon and theme park company may try to fight this, but they wouldn't stand much of a chance.
Ha, no. They would destroy you so utterly that even brave men would only whisper about you when safe behind locked doors, and as for the store itself, it would be smitten so hard that nothing but twisted weeds would ever grow on that spot again. You might want to read up on trademark dilution.
Real Programs don't use shared text. Otherwise, how can they use functions for scratch space after they are finished calling them?