look up any word:
1. sister slammer
The act of screwing your sister.
Not a name to be proud of.
Nasty, gross and wrong.
Usually due to country lifestyle.

see incest, inbred, redneck.
Random Guy: Dude, did you hear? Last night john screwed his sister.

Random Guy2: Ew... Bekka? He's a fuckin' sister slammer
rss and gcal