Hump-n-dump
Pretend to be in love in order to fuck a chick, and then dump her right away! Don't TELL her, just DISAPPEAR!
A person who DOES the hump-n-dump is called "Humpty Dumpty".
Hump n Dump
The act of having sex and then breaking up with that chick/dude immediately afterward.
Hey dude, you totally pulled a hump n dump last night with that chick! Right on brah!