look up any word, like dirty sanchez:
 
1.
The act of defecating after a person has engaged in anal sex and been the 'receiver'.

i.e. He did me in the ass so I took a humpdump on him.
Humpdump in your mouth yo!
by Jake Sklar November 28, 2004
 
2.
When a woman is vigorously riding a man in the reverse cowgirl position and loses control of her bowels, excreting feces onto the mans stomach and chest.
Barbie was riding my man meat so hard last night she took a massive hump dump on me.
by Funmunke April 22, 2010
 
3.
The act of following these steps:

1) Ask a hot girl out.
2) Fuck her.
3) Dump her.
Hey man! I gave Courtney the good old humpdump!
by johnr69 March 24, 2009