1. "Complaint box" = someone who complains a lot.
2. "Don't eat my head" = don't annoy me.
3. "Please adjust" = I am asking you to compromise or improvise to make this situation work.
4. "Kindly do the needful" = please do what is necessary (and get it done).
5. "Pre-pone" = to move something up (the opposite of postpone).
6. "PJ" = poor joke.
7. "BT" = bad trip, used by people in Delhi to describe bad experiences (not necessarily drug-related).
8. "Send" used to request the passing of table items, as in "send the salt, please."
9. "Mugging" = cramming for an exam.
10. "Passed out" = graduated, as in "passed out of college."
11. "Foreign-return" = someone who's returned home after living abroad.
12. "On" and "off" used as verbs, as in "off the lights, will you?"
13. "Only" tacked on the end of sentences for emphasis, as in "I am doing this only" (ie. right now, when asked about the status of a task).
Thanks to the BuzzFeed India team, who suggested phrases for this post.