'Big Brother' Houseguest Drops N-Word

"Big Brother" houseguest JC Mounduix hurled a couple of nasty epithets Tuesday night -- in front of a black houseguest -- while trying to explain how NOT to offend people. No joke.

JC, who stands 4'8" tall, was trying to explain the difference between the words "midget" and "dwarf" ... and told Bayleigh Dayton, who's black, it's like "gay and f***ot or ni**er and black."

The lesson did NOT go over well with Bayleigh, who quickly reacted in anger.

This isn't the first time a 'BB' houseguest has gone there. Kaitlyn Herman dropped the n-word earlier this month while singing a Drake lyric, and that was AFTER producers had warned them about offensive language. Oh, and there were the two women who said their tans made 'em "look ghetto."