The side note typically is only friends with one girl in the group leaving every guy and maybe even a few of the girls wondering where the hell she came from. Urban dictionary
I can't seem to find any other [reliable] sources which would agree with the definition above, which makes me doubt the credibility of the note. Furthermore, downvotes to the post were almost as much as the upvotes. So this leaves me with the following questions:
- Can "side note" actually be a person?
- Is the definition above correct?
- How common is this slang use of the word?
- If the answer to the questions above is positive, can a side note be a guy or is it only about females?
Please cite proof of the use of such expression (if any).