A long hard object used to fuck something incredibly painfully. This is usually done so in the anus or some other unconventional pore such as the eye socket or ear. A reamstick can be anything ranging from a lead pipe to an abnormally sized penis.
I was disappointed with the size of his Australian penis but it didn't matter once he got his reamstick from a the drawer next to the bed.
Victim fucked to death in the eye with this man's reamstick.