coup de main - noun
\ˌkü-də-ˈmaⁿ
Definition of coup de main : an attack that achieves complete surprise.

Matt Smith disguised as Bart Simpson at San Diego Comic-Con 2013.

Matt Smith walked the floor at San Diego Comic-Con this past weekend, whilst wearing a Bart Simpson mask.

Of course, he made a point of chatting to 'Doctor Who' fans [while in disguise]... but no-one really wanted to talk to him. Poor Matt!

"I tried to talk and make friends!"

Watch what happened below...