A sore thumb is any peer, teen, adult, child or person who on purpose stands up for their beliefs or ideas. A sore thumb rejects the popular way thus the term "sore thumb" refers to a way a finger is obvious when it is bandaged.
For example, a sore thumb would be a person standing up for their religion, while everyone else believes in no God at all.
The person can be unpopular, however doesn't care because it is the true way.
The person is NOT a tattle-tale or stuck up snob.
Sore thumb -6 people in an office are cheating the system and writing in that they worked an extra hour per day, and leaving. One of them realizes this is wrong, stands up for himself and does the right thing by writing it in correctly.