Need a good idea

My brother's getting married and he asked me to be the best man. I really want to do something funny for the reception. This is what I got to work with: both are gamers (Call of duty and Halo), my brother is anime fan her I don't know if she likes it. Could use some ideas,I wanted to do a flash mob or put on some armor like master chief from halo and congratulate him. It doesn't have to be funny it could be romantic too. I really want them to remember and have fun this day.

I don't really need a serious answer just what would seem interesting and entertaining to you guys to help me get a better understand. Go crazy

I don't really need a serious answer just what would seem interesting and entertaining .

Brother would kill me but seems interesting.That goes on the list of Maybe.

Then both will kill me with a rusted spoon. Family dinners will be very awkward for then on.