subbing
1. The act of adding subtitles to a foreign film. Primarily refers to the subtitling of anime that is (usually) unlicensed in places other than Japan.

2. Act of replacing an indisposed teacher for an impermanent amount of time.

3. The act of being on the bottom in a sexual act, usually BDSM.
1. X: Hey, have you seen such-and-such? GROUPNAME is subbing it.
Y: Yeah, they're terrible. OTHERGROUPNAME does a much better job translating.

2. Mrs. Whoswhatsit will be subbing for Mr. Thatoneguy today, because he is sick.

3. X: Why is Z chained to the bed?
Y: He's subbing.