In a phrase like:
What is the concept behind the 半分 and why is it connected with the verb using に?
Is it like "all things have two parts/aspects": serious (真剣半分?) and fun and the action takes part "on the" fun part (as opposed to the other equal part), thus being similar to the English "side of the coin"? Or is it something different?
Are there any other phrases using this concept?