Used in the same context as asshole and meaning the same thing, assel is less conspicuous and far less noticeable to someone who doesn't know what it means.
The coolest girl to ever walk this planet. Her amazing style, her marvelous personality and let's not forget her incredible football skills. She is so loved in this world by everyone around her, she's the type of person who just brightens up everybody's day without even knowing it. She's the best friend / girlfriend anyone could ever ask for, by being there for you when you need her. Assel is also a magician, superhero, an artist and let's not forget she's a genius with the biggest brains ever. I love you baby!
An assel is a tassel spun or twirled by a performer on their behind. Not to be confused with a 'tassel' commonly used by burlesque performers on their breasts. 'Ass' + 'Tassel' + 'Assel'.
Did you see that? They were spinning their assels so fast I thought they were going to take off.