Pulled a Jimmy

When you are singing, humming, mouthing, or whistling a notoriously famous song, and some guy, be it a friend or someone you don't know at all, starts singing the words to the famous song with you timidly and awkwardly, making you stop singing immediately. Typically the theory of "pulling a Jimmy" can be tested by walking towards the person in question, and singing "we are the champions." If the person joins you a couple words in, he is deemed to be pulling a Jimmy. **Warning** avoid singing around these people once you have caught on to them! Or better yet.... try and see how many times in a row you can get the fool to join you in singing gayly and then tell all of your friends!