mirrajay, yup that is one theory... But, there are other theories... Like, 'you teach people how to treat you' for example.
Because, teasing can turn into bullying. Even with adults.
Recent international psychological research on 'Bullying' has actually found that ignoring insulting and offensive comments by both adults and children often inadvertently contributes to the comments and situations escalating, due to the newly empowered perpetrators feeling of control and superiority actually increasing over their victims, based upon, and socially reinforced by, a lack of consequences for their actions.
So, it could also be dependant on the extent of the teasing, and the personality of the person doing the teasing... And, of course, intent.
Sometimes 'ignoring it' can actually make the situation much worse.
Of course, NOT all teasing is bullying! But, if it is consistent teasing, from one person or one specific group of people, it might be 'bullying' rather than teasing.
But, for the most part, random UK people generally teasing random Americans would not be considered 'bullying.'
Now, if it is one person, any person from anyplace, doing it over and over again... We all might want to look at it a bit closer.
I just found that research outcome to be interesting...