Bearing witness to a particularly pleasant ass, which is both fit and capable of strenous activity.
Damn Holmes, witness the thickness!
(As a woman with an attractive rear end walks by.)
Indeed Watson, quite an assadocious young lady...
Possessing an overly proud ass; bragging about the excess of ass.
All the boys flocked to Liz because she was so Assadocious; her ass was thick and fine.