In a more narrow linguistic definition, Code-Switching means the intermixing of at least two languages when speaking or writing. It's most common between people who know two+ languages or is learning another language. Some examples including:
Speaking Spanish in one sentence, and then switching back to English in another sentence (with or without thought)
Speaking French but inserting a few Spanish words (and vice versa) with people who know how to speak both French and Spanish. A crude example would be "Hola! Je m'appelle Rail Tracer", or "Bonjour! Me llamo Rail Tracer." To a person who can speak both Spanish and French, it'll be understandable (people that try not to intermix the two languages will just think it's weird)
Speaking Chinese but inserting an English word by accident without realizing that it was an English word you were using (that has not gone through the process of loan-words, like how Sushi or Dim-Sum has become a common English word.) An example: "我在找一 bowl." The characters used in the majority of the sentence is said in Chinese, but the person decided to use bowl instead of 碗 (which is a bowl in Chinese.) Roughly (I think) translate to "I am looking for a bowl."
Yes, it is particularly common with me because I am bilingual (but still trying to get better at my lesser used language.) Sometimes I'd speak in my second language and then I'll end up interjecting English words and sentences here and there without thought. Relatives/friends that cannot speak both languages will start raising eyebrows while relative/friends that can will completely understand what I was saying (because they do it also.)