When the DM asks, "Are you sure?"

[Slipperychicken]

I'm usually absotely disgusted if the DM tries to manipulate me. However, I don't show him/her that and I keep my thoughts to myself.
I will just ask him "why?". In most cases, the DM will talk me out of it, but I won't be happy with the manipulation. In some cases I just go ahead, simply just to demonstrate that it's my character.

Do you mean when the DM only asks "are you sure?" when he sincerely thinks the action is unwise, or when he does it to psych you out/throw you off-guard?

In my personal experience, the DM usually accompanies the "are you sure?" with a bit of crucial info that I could have easily missed or forgotten (things like "he's holding a hostage", or "his bodyguards are all around"), so I consider it helpful.