To everyone prepping for interviews,
I'm a 13D admit and both my interviews were a lot of fun...
The first one was a little nerve-racking because the interviewer kept this mask-like face on (details earlier on the thread) but the second lasted 2.5 hours and I never realized it.
The interview is essentially to gauge your fit. If you've made it to the interview stage, then you're fine in terms of work-ex, essays, gmat etc etc. Now it's about how you can prove you're a fun person, a team-player, level-headed and 'human' and most of all, given the INSEAD values, how you can contribute to INSEAD (classroom, clubs etc).
Just be yourself. The interviewers are senior people, they know how to gauge people and they'll see through any pretensions in a jiffy.
Praveen's put together a fine list of questions, but as Deepak pointed out - look for the bouncer. The ClearAdmit Wiki has some good leads as well...
Happy to help with any further questions
Cheers!
V