Well, it’s almost always the more physically stronger person who gives it to the “weaker” person. I think when a dad does it to his son, it’s just good old fashion horse play.
1. Receiving a noogie is an unpleasant sensation.
2. The person giving the noogie enjoys imparting this sensation on their "victim" and seeing the reaction.
3. A sadist is someone who gets pleasure from inflicting pain.
4. Getting pleasure from inflicting unpleasant sensations on people may not be full-blown sadism but it clearly has some similarities. There is the same quality of delighting in the misery of another person.
I think when a dad does it to his son, it’s just good old fashion horse play.
My young son likes to play fight but I would never intentionally hurt him for my own gratification.