From SA Mafia Wiki
tr.v. sur·prised, sur·pris·ing, sur·pris·es
1. To encounter suddenly or unexpectedly; take or catch unawares.
2. To attack or capture suddenly and without warning.
3. To cause to feel wonder, astonishment, or amazement, as at something unanticipated.
4. a. To cause (someone) to do or say something unintended.
--- b. To elicit or detect through surprise.
1. The act of surprising or the condition of being surprised.
2. Something, such as an unexpected encounter, event, or gift, that surprises.
In most mafia games, one can expect to be surprised at least occasionally. Players may do and say things you did not expect. Likewise the setup may be something you did not expect as well; this is the case for most closed setup games, since by definition you wouldn't know what's in it. It could have no doctor; it could have five doctors!
When you join a game of mafia, it is assumed you will be surprised about something sooner or later. Anticipate it! Love it! Learn from it!
And don't bitch about it.