(Not to be confused with 'Par' or 'Raw Par')
Girl 1 (17) is going out with Boy 1 (20).
Boy 2 likes Girl 1 and Girl 1 likes Boy 2.
In fact, Girl 1 likes Boy 2 so much that she dumps Boy 1 to be with him.
This could be described as a 'Classic Par'
alternatively, it could be said that Boy 2 'Classically Parred' Boy 1