when a woman looks like she has a flat ass, but upon removal of her clothes you notice that she has a surprisingly shapely ass, she has a surprise-a-donk.
in the movie Black Swan during the masturbation scene, Natalie Portman has a surprise-a-donk.
The Urban Dictionary Mug
One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.
Buy the mug