Acronym; stands for "Hard Core Fuckin'". Very useful when describing what you did last night when in the presence of a group that includes your girlfriend, who subsequently was stuck at work on the night in question.
He said he was HCF'in last night, which is strange because he was at a family reunion.
acronym which stands for "Back Fat Fuckin'". Achieved by pushing together two rolls of fat on some fat slut's back and pumping away. A good technique when the rotund cum-dumpster you're rogering has a hatchet wound so loose that it's like throwing a hot dog through a hallway.
You'll get that new aggressive full-blown AIDS if you bone that slutty keg-on-legs.